WHAT'S THIS FOR: Sufficiently installing and removing the bottom brackets of Traditional Tapered, Shimano Octalink, and ISIS Splined. COMPATIBILITY: Compatible with any 20-tooth cartridge type bottom bracket. WHAT PAIRS WITH THIS Use it with a 1/2" drive wrench or a 24mm open-ended shifter spanner. Recommend using a 1/2" drive wrench with ratcheting handles or torque wrench for better installation. QUALITY MATERIAL Made of heavy-duty steel to make this tool is more durable and reliable. It will not easily get worn out after years of use and is “bottom bracket friendly”.