... durable. automatic feeding device is optional. rolling shape: rolling thread, textured, ruled, roll bars etc Model: FR-30*50 ... diameter: 78(90mm)Roller inner diameter: 25.4 (35)keyay 10*3Wheel Thickness: 20mm 40mmThe distance between wheel axles: 90-55mmWheel ... .6, Automatic feeding device is optional.7, rolling shape: rolling thread, textured, ruled, rolling light, cross knurling, roll bars, rolling ...