I DID know what that was for!? BUT in all the years in Brit land in the late 40s and early 50s I NEVER EVER saw one. But then we and lads where ONLY intersted in GOING FAST! NOT Coasting. Also the fork blades looked a little different to the ones we had in those times, Cheers John Crump OldNOWimcoastingBrit, Parker. Co USA