by Kaotik » 3 Mar 2007 13:46
An 1/8" would be a safe measurement, most street sweeper bristles are an 1/8" and many members here have good results using them as tension wrenches and picks.
You will also find that both sizes of windshield wiper inserts are not 1/8", one is thinner the other is wider...though the thinner one is good for really small locks and good for use at the top of the cylinder near the key pins.