Buttonhead Titanium axle bolts are light- .7oz (20g). They will fit Profile BMX Mini (3/8) Hubs, MicroMini Hubs, Totem (3/8) Hubs and Profile True 3/8 Fixed Hub axles. They take an 8mm Allen key. There are two versions- one fits 3/8″ dropouts (A.), and the other has a step so it will fit in a 14mm dropout (B.). You can also purchase one of each style, so you can run the Ti bolts on your non-peg side. Not intended for use on the side of your axle you run pegs on.