"Lightweight aluminum 6061-T6 inner body with SPS adjusting system. SPS uses two washers and a coned insert and bolts instead of four regular washers and nuts for more precision and easier adjustment. Female washer avoids nut sticking out" COMPOUNDS There are 3 different compounds on the different colors. Here they are: -SOFT (clear colors, clear rubber ). For those that want a very effective brake with least feather. (They can be a bit noisy depending on rims and conditions). -MEDIUM: (black, white, purple). Standard compound with good braking and normal feather. -HARD: (Red) For those that want a very stiff pad and more feather. Also for use on chrome rims to avoid noise. Weight: 1.12oz/32g (pair)