School Smart Premium Felt Chalkboard Eraser measuring 5 in L x 2 in W x 1 in H ensures better cleaning and longer life. Eraser feature six strips of high quality black and white erasing felt that are dual sewn with strong nylon thread to a rigid inner felt back offers durability. Felt back is laminated and double lock-stitched creating a full 7/16 in thick, non-breakable back.