TPR (thermal plasticized rubber) is resilient, non-marking, stronger than black rubber and softer than polyurethane. Non-marking TP Yellow Rubber. 5 year warranty. Shaft size is 1-1/8" (2.54 cm) but can be reduced to 3/4" (1.91 cm) by supplied bushing. Dimensions: 5" Width x 1-1/8" or 3/4"