The Shimano BB-UN300 Bottom Bracket is designed for road and mountain bikes with a 68mm shell width and a 122mm spindle length. Made from a combination of aluminum and steel, this bottom bracket features a square taper spindle type and is compatible with BSA (English) bottom bracket shells. The sleek black and silver color scheme adds a stylish touch to your bike while providing durability and performance for all your cycling adventures. This set includes one bottom bracket and is a crucial component for maintaining optimal functionality on your bike.