pucks will split after a few years. they are made out of polyurethane with a hardnest of 40 with a rubber shell, another alternative is to make molds and use liquid poyurethane called devcon/80, dont get the 90 or your rig will vibrate like a mofo due to it being really hard, i used the this for making solid motor mounts and have made several sets and all have held up one, set was installed in a 800hp camaro, hockey puck were only suggested because it would be the cheaped if you had to buy any items or supplies,devcon cost about 45$ a quart