This is a brand new Meroca Black Aluminum Bicycle M20 Crank Arm Fixing Bolt. These crank arm fixing bolts are black and made of aluminum. They are compatible with Shimano crank arms that use a M20 fixing bolt. See below.

Fits on these Shimano Road bike crank arms - FC-R4700/R2000/R3000/R5800/R6800/R7000/R8000/R8100

Fits on these Shimano MTB bike crank arms - M4000, M590, M596, M661, SLX, XT, XTR