Nukeproof warhead steel headset bearinggenuine replacement warhead ac cartridge bearing form nukeproof sb a 30mm replacement bearing for all 1 18th nukeproof headsetssb b 40mm pre 2015 replacement bearing for 15 nukeproof headsets pre 2015sb b 40mm 2015 onwards replacement bearing for 15 nukeproof headsets 2015 onwardsspecificationssb a 30mm 410 x 45 x 45sb b 40mm pre 2015 518 x 36 x 45sb b 40mm 2015 onwards 518 x 45 x 45buynukeproof componentsfrom chain reaction c