IRONguard R Model Rubber Molded Dock Bumper, Rectangular, 4 Holes, 13" Length, 12" Width, 4" Depth 4" Projection Manufactured from reinforced prime rubber Impact recovery of 98 percent plus or minus 2 Tensile strength 8.3 N/mm2 plus or minus 0.5 (ASTM D792) Elongation of 500 percent plus or minus 20 (ASTM D792)