Draper expert 4 piece 1 2 square drive wobble extension bar set draper expert 85187 b i expert quality i b manufactured from chrome vanadium steel hardened tempered chrome plated and polished for corrosion protection enables sockets to be driven at up to 15 176 to the vertical spring loaded ball bearing for secure socket holding overall lengths can vary in production display packed br br b manufactured and tested generally in accordance with din3122 and iso3315 specificatio