Frag swaps are usually run in one of two ways or a combonation of them both.
People bring frags of their corals either Sps
, or any type and acually swap coral for coral with others. Idealy the corals are brought in small plastic tubs with saltwater in them or in quality ziplock bags.
Another way of running the frag swap is to bring frags with the intent on selling them for $ and purchasing other frags for $.
Then you have the combo method where you may swap frag for frag on some items or you might pay/sell other frags.
Frag swaps are great because for every coral you aquire this way its one less coral that has to be pulled from the ocean. Its also advised to frag the frag you get at a swap and give/sell it to others once the inital frag is large enough.