Klaxon (Twist); Klaxon (Twist R)

The TWIST and TWIST R are add-on motorized drive units that attach to manual wheelchairs to provide auxiliary power, reducing the pushing effort required by users. They are designed for active wheelchair users weighing up to 120 kg who are physically and mentally capable of safely controlling a manual wheelchair. The devices come in two variations with up to seven different configuration options (front or rear mounting, with or without handlebar, user or attendant control).

Both devices use a 250W brushless motor, 36V lithium-ion battery (4Ah, 144Wh), and Bluetooth Low Energy wireless control. The TWIST offers five configurations including front-mounted options with an optional handlebar (10 km/h max speed) and rear-mounted options (6 km/h standard, 10 km/h optional); the TWIST R is simplified with two rear-only configurations. The subject device achieves a range of 21 km versus the predicate's 20 km, and includes electronic braking and speed limiting on downhill slopes for front-mounted variants, whereas the predicate relies on freewheeling.

ISO 7176 series (Parts 1–4, 6, 8–11, 14–15, 21–22) covering wheelchair stability, dynamic stability, brake effectiveness, energy consumption, speed, strength, climatic performance, obstacle climbing, test dummies, friction, power/control systems, EMC, and setup procedures. Also cited: IEC 62133-2 and UL 62133-2 for battery safety, IEC 62304 for software lifecycle, EN 12184 for powered wheelchairs, ISO 10993 series for biocompatibility, EN 60335-2-29 for charger safety, and ETSI/FCC standards for electromagnetic compatibility and wireless coexistence (ANSI C63.27-2021, TIR69:2017).

The subject device shares identical indications for use, intended user population, and operational environment as the predicate SMOOV O10 (both are add-on drives for active wheelchair users). Key technical differences—such as the subject's lower maximum user weight (120 kg vs. 140 kg), different wheel diameter (10" vs. 6.4"), enhanced braking capabilities on front-mounted variants, and stepless speed adjustment via handlebar throttle versus click-wheel selection—do not adversely affect safety. Both employ the same motor and battery technologies, undergo identical ISO 7176 testing protocols, and the subject device's front-mounting configuration actually provides improved safety through reduced tipover risk and active speed control on slopes. The predicate's clearance (K192016, dated 2020) establishes that this class of device is safe and effective; the subject's design enhancements and tighter weight limit mitigate rather than introduce risk.