Zinc-plated steel. Two 6 1/2" adjustable wheels on a 1/2" x 24" shaft. Designed to be used with a heavy duty 1/2" to 1" drill of 450 to 750 r.p.m. for mixing thick materials in 12" diameter 5 gallon pails. For mixing in 55 gallon drums, wheels can be spaced further apart.