aluminum alloy^^The electric window motor built in overload protection system. It can avoid the motor burning out as the high electric current. ^^High quality two-layers stainless steel chain, which makes the chain stronger and more anti-oxidate^^The short pitch chain 08B-2 can ensure the low noise and stable operation of the automatic window opener. ^^Travelling distance is adjustable to 3.94 inch/ 7.87 inch/ 11.81 inch/ 15.74 inch, you can easily set it by yourself^^Transformer function is built in motor, no need extra transformer or receiver, input voltage AC100V-AC240V is workable with electric chain window opener