1、MTB bike hub towers base for 8/9/10 speed cassette flywheel. 7 speed flywheel needs to be used with washers (not included). 2、Made of high-quality chrome molybdenum steel, forged and high temperature heat treatments, high strength and nice lubricity. 3、It can help solve the problem of wheel idle slippage, avoiding replacing the whole hub or wheel, convenient and save money. 4、Easy to install and use, a variety of towers base structures are available, please confirm whether it fits before purchasing. Features: bike hub towers base for 8/9/10 speed cassette flywheel. 7 speed flywheel needs to be used with washers (not included). Made of high-quality chrome molybdenum steel, forged and high temperature heat treatments, high strength and nice lubricity. It can help solve the  problem of wheel idle slippage, avoiding replacing the whole hub or wheel, convenient and save money. Easy to install and use, a variety of towers base structures are available, please confirm whether it fits before purchasing. Specifications: Color: Black Material: Chrome Molybdenum Steel Speed: For 8/9/10 Speed Cassette Flywheel Type: Locking-Teeth Ball Type/ Locking-Teeth Bearing Type/ Plum Flower Ball Type/ Plum Flower Bearing Type(optional) Item Weight: Locking-Teeth Ball Type: 173g/ 6.1oz Locking-Teeth Bearing Type: 172g/ 6.1oz Plum Flower Ball Type: 181g/ 6.4oz Plum Flower Bearing Type: 179g/ 6.3oz Packing List: 1 * Bike Freehub 1 * Bike Freehub