When sourcing electric wheelchair attachments (often called power trikes or handcycles), you must prioritize motor power (typically 250W to 500W) and battery capacity (Lithium-ion, 36V/48V). Ensure the climbing capacity is at least 8-10 degrees to handle ramps. The attachment mechanism is critical; look for universal clamps that are compatible with both folding and rigid frame wheelchairs. Additionally, verify the braking system, preferably dual disc brakes, to ensure user safety during high-speed operation (up to 20-25 km/h).