The new PENROC 55 bags have arrived. Substantially less plastic and transport packaging. Still the same excellent PENROC. PENROC 55 The new bag contains 55 PENROCS covering an area of approximately 23" x 11" or 575mm x 275mm Lava rock replacement for gas & electric grills Cleaner � Less flare ups � Tastier food. PENROC is designed to replace the lava rock on your gas barbecue --- giving you the authentic aroma of a charcoal barbecue. The distinctive design of PENROC allows the fat from your cooking to simply roll off. This prevents messy clogging and minimises the chance of flaring. PENROC is manufactured using slate and ceramic with a mixture of fine oakwood particles and purified charcoal. The mix is then hardened to the distinctive PENROC shape for long lasting and hard wearing use.