Shimano FD-A400 is a front derailleur designed for double gear use, compatible with narrow-type chains only. It features a stroke of 37 to 51mm, an installation band diameter range of 1-3/32" to 1-1/8", and a capacity for a front gear tooth difference of 3T to 14T. Its chain guide can be adjusted for low and top positions to prevent contact with the chain. The derailleur is secured to the frame with a 5mm allen key.