aluminum alloy^^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 window opener. ^^The motor built in overload protection system. It can avoid the motor burning out as the high electric current. ^^The surface of the opener housing has electrophretic precossed. ^^The products have gone through thousands of tests with CE certification.