Abstract: A holder device is provided for attachment to a wheelchair or other mobility equipment. The device has a surface that is at least partially bounded, with the bounded portion forming a slot. The device has a first holder magnet at the surface adjacent a terminus of the slot and a second holder magnet at the surface spaced apart from the first magnet. Also provided is a system for fixing an accessory to a wheelchair or other mobility equipment. The system has a holder device, such as that described above, and a sliding member for interfacing with the holder device. The sliding member has a sliding surface for mating with the holder surface, a first sliding magnet at the sliding surface of the sliding member, and a second sliding magnet spaced apart from the first sliding magnet.