Halo"s Coilex construction consists of a screw-type thread molded into the baffle that looks nice and does a better job of eliminating stray light than a regular step-type thread would. You can order custom trim rings, too: the TRM6 line offers you a variety of finish options, and if you cut your opening too large, the oversize trim ring (#OT403) can cover up your mistake. If you want to be able to aim your light, you can also order the R/PAR-lamp-aiming accessory (#H930).--Josh DettweilerWhat"s in the Box Coilex baffle, trim