1.Material:Metal, 2.Used to remove crank arms this tool needs either a 16mm and a 19mm spanner or just an adjustable. 3.It is incredibly simple to use and requires no rocket science. 4. Remove the bolt in the crank arm using the back of the tool. 5. Screw the lower black part of the tool into the crank till tight (ish) . 6. Screw in and continue to tighten the silver piece of the tool until the crank starts to move. 7.Easy to use. 8.Use for bike Square Crank 9.Use for ISIS CRANK WITH THE BLACK CAP 10.14mm socket wrench Use for remover bolt of bike bottom bracket . 11.Unit weight:124g.