Pulley rib. Alternator pulley and it broke so I just cut it off and bought a $40 guaranteed pulley and it was a lot stronger. Wouldn't recommend it to anyone who isn't a professional mechanic without the right tools or skills. Maybe I'm just a fool and ruined everything. But same process with the second one and it was much stronger and went through 2 times with no problem. hp Change the thermostat before the belt because it will have to come back soon to be replaced.