MIG Drive Roller 

30.0mm dia x 10.0mm wide x 10.0mm Bore
0.9-1.2mm
TREO style Roller
KNURLED 

Part No: RK301010.09.12
FCW Drive roll kit FLUX Cored wires
Suits Bossweld TREO 175 & possibly many more (MIGOMAG?).
Knurled drive wheels reduce slipping when using flux cored wires.
Requires less tension on idle wheel.
Wheel Size diameter 30.0mm x 10.0mm wide x 10.0mm Bore + (keyway 3.0mm )
PHOTO for display ONLY read dimensions & wire sizes given