100% Microfiber Spin Mop Refill: These mop heads are made of 100% super absorbent microfiber strands with a soft absorbent cord that will not scratch the floor surface. Our mop replacement head is very suitable for mopping all hard surface floors. High softness and super absorbent for easily cleaning tough dirt and grime without scratch the floor surface. 8Pack Spin Mop Replacement Head: The Inner triangular rim size 3.9 inch and the outer triangular rim size is 5.6'' in diameter, Perfect replacement mop head for triangle Spin Mop system.