Boston Aqua Farms coral Reef Plugs™ are specially designed to take advantage of all the best qualities of other plugs and coral frag mounting solutions to date. The plug resembles a small one legged table. The peg in the bottom is designed to fit nicely into eggcrate, it will also fit nicely into a small crevice or hole in your live rock. (Some drill 3/8" - 1/2" holes throughout their new live rock, to provide future resting places for our frag plugs.) The top is about 1" in diameter and sports a layer of bright reef sand that helps corals and coralline algae to adhere more quickly, it also looks more natural then aragocrete.