Tenergy 05 Hard has adopted a stiffer sponge to add further power to the original Tenergy 05 rubber. While it still maintains the incredible ‘Spring Sponge’ feel, the hard sponge responds to a stronger impact enabling more power. Please use Free Chack II when you apply Tenergy to a blade. Tenergy is a highly delicate product. We recommend you protect the rubber surface with rubber protective film after a match or practice. Tenergy Family Rubbers, realize your more!