No catch, I've been using one for a couple years now and really like them. Be sure to check the Temperature ratings, the plain one is rated at 35 degrees, you will need one of the models with insulation inside for colder ratings. I just used my 35 degree pad on a 25 degree overnight camping trip, tent on snow and I was cold with that pad. I put my pack and all extra clothing under it which really helped. I will be getting the insulated core model for any future winter camping.