Keychron has just expanded its line-up of K Ultra wireless mechanical keyboards with the K4 Ultra and K10 Ultra, both of which feature num pads and identical internals with slight layout tweaks to cater to different use cases. The K10 Ultra is a full-size wireless mechanical keyboard, replete with a four-key macro row above the num pad, while the K4 Ultra forgoes the navigation cluster above the arrow keys in favor of a more compact 96% layout, although it keeps the small blocker area between the main alphanumeric cluster and the num pad. Both the K4 Ultra and K10 Ultra are available on Keychron's online store and its Amazon storefront for $114.99. The K4 Ultra's compact layout slims down the overall footprint by just over 55 mm, with the K10 Ultra measuring in at 447.76 × 139.82 mm compared to the K4 Ultra's 391.29 x 140.27 mm.

Internally, both the K4 and K10 Ultra are based on ZMK firmware, which optimizes for wireless battery life, with Keychron claiming up to 600 hours of battery life from the 4,000 mAh battery in both keyboards with the backlighting disabled. For wireless connectivity, the K4 Ultra and K10 Ultra feature 2.4 GHz and Bluetooth 5.2 connections, with a USB Type-C port for charging or wired connectivity, and both keyboards are capable of 8 kHz polling over 2.4 GHz and wired connections. Both keyboards are based on the same physical design, which combines a tray-mounted ABS case, a steel switch plate, and various internal sound damping materials for improved auditory feedback. The K4 Ultra and K10 Ultra use double-shot PBT keycaps in Keychron's OSA keycaps, which have the same height as OEM profile but with a slightly more retro design language. The K4 Ultra and K10 Ultra are available with three different box-stem switch options: Keychron Apex Red (linear with 45 gf actuation force and 2 mm actuation distance), Brown (tactile with 50 gf actuation force and 2 mm actuation distance), and Banana (tactile with 55 gf actuation force and 2 mm actuation distance).