Amazon is currently selling the Logitech K400 Plus on Amazon Wireless Touch TV Keyboard for $27.03 — 23% below the keyboard’s standard $35 list price — putting one of the most capable PC-to-TV input devices in the budget peripheral market at one of the best prices it has reached as a new unit on the platform. Before you click “add to cart,” there is one quick firmware step worth knowing about — a patched wireless security vulnerability in the keyboard’s RF receiver that is worth a two-minute fix once the keyboard arrives.

For anyone who runs a PC through a television — whether as a proper home theater PC (HTPC), a Raspberry Pi media server, or a Steam gaming rig — the K400 Plus fills a niche that surprisingly few competing products do: it combines a full-size keyboard layout with a touchpad in a single lap-friendly device, eliminating the awkward problem of needing a flat surface to use a separate mouse from the couch. At $27, the decision calculus is simple for that use case. Understanding the underlying wireless technology, and its one documented limitation, makes the decision even clearer.

The K400 Plus has appeared at roughly $28 on Amazon multiple times throughout 2026, with the Gizmodo October write-up describing it as having gone through K400 Plus price history on Amazon multiple price drops over the year. The $27.03 price point sits at or near the floor for new units on the platform. Prices are subject to change.

How Logitech’s RF Connection Actually Works — and Why It Is Not Bluetooth

The K400 Plus communicates with a host computer through Logitech’s Unifying receiver, a small USB-A dongle roughly the size of a fingernail. Unlike most wireless keyboards sold in 2026 — which use Bluetooth Low Energy — the Unifying receiver operates on a Logitech Unifying receiver protocol built on a Nordic Semiconductor nRF24L-series chip transmitting on the 2.4 GHz band.

That is not an arbitrary design choice. The proprietary RF protocol presents itself to the host computer as a standard USB HID (human interface device), which means no Bluetooth stack, no pairing negotiation, and no driver installation. For a TV-connected PC that may be running a minimal Windows installation, a ChromeOS device, or an Android TV box, that simplicity matters. The receiver also supports frequency hopping across the 2.4 GHz ISM band to avoid interference from Wi-Fi routers and other devices operating in the same spectrum.

The K400 Plus wireless range specs are 10 meters (33 feet) — enough to reach across any typical living room. The 18-month battery life on two standard AA batteries is achievable because the nRF24L chip enters deep sleep states between keystrokes; the device only transmits when actively in use, and at living-room usage rates, the duty cycle is extremely low. The keyboard includes an on/off switch to eliminate standby drain entirely when the keyboard is stored.

Does the K400 Plus Work With Bluetooth Devices? No — and That Matters

The single most important limitation to understand before buying: no Bluetooth on K400 Plus — it requires a USB-A port on the host device to accept the Unifying receiver dongle and has no direct wireless connection mode without the dongle.

That rules it out for tablets and phones without USB-A ports, for modern laptops with only USB-C connections (unless you use a USB-C-to-USB-A adapter), and for any multi-device workflow where you need to switch the keyboard between two computers quickly. For a dedicated HTPC, a Raspberry Pi with standard USB-A ports, or a PC plugged permanently into a TV, the limitation is irrelevant. For everyone else, it is a deal-breaker.

Logitech introduced a successor wireless platform — Logi Bolt launched in 2021 — using a different RF protocol with lower latency and improved enterprise security. It is incompatible with the K400 Plus’s Unifying receiver; the two systems cannot share a dongle or pair with each other.

Does the K400 Plus Have a Known Security Vulnerability?

Yes — and it has been patched. In February 2016, security firm Bastille Networks disclosed a vulnerability in the Logitech Unifying receiver identified as CVE-2016-10761 MouseJacking vulnerability. The flaw allowed an attacker within approximately 100 meters (328 feet) to inject malicious keystrokes into a computer through the Unifying receiver’s RF link, bypassing the receiver’s encryption.

Logitech issued a Logitech firmware update February 2016 for the Unifying receiver in the same month the vulnerability was disclosed. However, because the K400 Plus was introduced in 2015 and units manufactured before the patch release were shipped with unpatched firmware, receivers purchased or stocked before February 2016 may still carry the vulnerability — and 2019 research on unpatched dongles found that new-in-box Logitech devices purchased from retail contained unpatched dongles manufactured before the fix.

The fix is straightforward: Logitech provides Logitech’s free firmware update tool through its software utility suite. Current guidance from Logitech directs users to Logi Options+ (the successor to the older standalone Firmware Update Tool) to manage and update Unifying receiver firmware. Run it once after plugging in the dongle, and the vulnerability is closed. Given the age of the K400 Plus product line and the supply chain uncertainty, any new-to-you unit is worth patching before use — particularly if the keyboard will be used in shared spaces, offices, or anywhere an attacker could realistically position themselves within 100 meters (328 feet).

What Is the K400 Plus Good At?

With the security context established, the K400 Plus is a well-reviewed, durable product in a category with very few strong competitors. It earns high marks on the specifics that matter for living-room use: quiet, low-travel chiclet-style keys that do not disturb television audio at low volume; a built-in touchpad measuring approximately 3.5 inches diagonally (76 mm × 46.7 mm [3 in × 1.8 in] by dimension) with adjustable cursor speed; and a form factor sized to hold comfortably in one hand or lay across the lap.

The keyboard includes dedicated media hotkeys — mute, volume up and down, power on/off — that function on Windows and Android without any software installation. Logitech’s optional Logi Options+ software (formerly Logitech Options) enables additional customization of key assignments and touchpad behavior, but it is not required.

The K400 Plus product specifications include keys rated for 5 million keystrokes, a spill-resistant build, and plastic components made with 60% post-consumer recycled content. The keyboard ships with two AA batteries pre-installed and weighs approximately 390 g (0.86 lbs) without batteries.

Where it falls short is equally well documented: the chiclet keys have minimal tactile feedback and no backlighting, making typing in a dark room difficult. The arrow keys and touchpad click buttons are on the small side. The keyboard layout is full-width at the alpha keys but compressed at the edges to accommodate the touchpad, which can create muscle-memory friction for fast typists.

Is the K400 Plus Better Than the K830?

Logitech’s K830 is the next step up for buyers who specifically need backlighting, Bluetooth connectivity, or a rechargeable battery. It supports both Bluetooth and the Unifying receiver, making it viable for multi-device setups. It does not carry the MouseJacking vulnerability in the same way because the Bluetooth path has its own separate security architecture.

The K830 carries a significantly higher price — typically $80 to $100 — which puts it in a different decision bracket. For a dedicated PC-to-TV setup with permanent USB-A access and a predictable lighting environment, the $27 K400 Plus makes more sense. For a hybrid setup or a dark living room, the K830 is worth the premium.

Who Should Buy the K400 Plus Right Now?

The $27.03 price makes the K400 Plus a compelling buy for HTPC users, Raspberry Pi and home server operators, and anyone with a PC connected to a television who has been managing with a regular desktop keyboard and separate mouse. The price range for this keyboard on Amazon as a new unit typically sits between $28 and $35, with occasional sale events near the current price.

The one required step before using any Unifying receiver-equipped keyboard: download and run Logitech’s firmware updater via Logi Options+, confirm the receiver is patched, and then enjoy the couch. Prices and availability are subject to change.

Frequently Asked Questions

Does the Logitech K400 Plus work with Bluetooth?

No. The K400 Plus uses Logitech’s proprietary 2.4 GHz RF Unifying receiver, which requires a USB-A port on the host device. It does not support Bluetooth and cannot connect wirelessly without the included USB dongle. Buyers who need Bluetooth connectivity should look at Logitech’s K830 or other keyboard models that explicitly list Bluetooth support.

What is the MouseJacking vulnerability, and does it affect my K400 Plus?

MouseJacking (CVE-2016-10761) is a 2016 security disclosure by Bastille Networks that found the Logitech Unifying receiver allowed keystroke injection from up to 100 meters (328 feet) away. Logitech patched it with a firmware update released in February 2016. If you buy a K400 Plus today, run Logitech’s firmware updater via Logi Options+ once after setup — units manufactured before the patch date may carry unpatched firmware, and the fix takes only a few minutes.

What is the difference between the Logitech K400 Plus and the K400 (original)?

The K400 Plus (2015) improved on the original K400 with a refined touchpad that offers adjustable cursor speed, dedicated Android hotkeys, updated media controls, and a spill-resistant design. Both use the same 2.4 GHz Unifying receiver system and have the same 10 m (33 ft) wireless range. The K400 Plus also added compatibility with Android 7+ and ChromeOS, whereas the original K400 focused primarily on Windows.

Is the K400 Plus a good keyboard for gaming on a PC connected to a TV?

For navigating gaming menus, game launchers (Steam Big Picture Mode, GOG Galaxy), and streaming within a gaming session, yes. For active in-game play — aiming, fast keystrokes, precise timing — no. The K400 Plus is a living-room navigation keyboard, not a gaming keyboard. Its touchpad is not suitable for mouse-aiming, and the chiclet keys have limited tactile feedback for fast-paced typing. For a PC gaming HTPC, consider pairing the K400 Plus with a wired or wireless gaming mouse for gameplay, and using the keyboard for everything else.