Marco Rock Frag Mounts 9lb Bag of rocks provides a versatile selection of Reef Saver, shelf, single, and two-side cuts, making it the ideal choice for mounting coral frags in any setup. These rocks are porous yet heavy, ensuring stability and preventing frag relocation, unlike traditional frag discs. Trusted by professional aquaculture facilities for years, this premium mix is now available to hobbyists, offering the perfect balance of functionality and aesthetics for aquascaping.