Cast Iron V-Groove - VG. Wheel face and V-groove are machined from heavy duty cast iron. A relief groove at the base of the V tends to equalize the load to each face of the angle track when in operation. Wheel face and bore are machined for concentricity to proper tracking. These wheels can be used not only on track but flat surfaces as well. VL wheels feature a larger bore for greater capacity. Please note: Track alignment is critical when utilizing v-groove wheels.