Garage Dodr Motor 1)Aluminium alloy,solid and light 2)Both electric ... Rotation (r/min)Chain NO. 220V 50HZJM600-1P6.560068004126.210A 1) Relative humidity: 90% (25°C)2) Short hour ... Security mechanism in case chain is broken, (state patent)Future:1) Shell: Aluminium alloy , solid and lingt but durable and ... future.Best regards, ----ZhangZhou JinAn Electric & Machine Co.,Ltd. Roller Motor For Garage Door