Altra Service Professionals is a medical equipment service & repair company located in Ocala, FL. We service most respiratory equipment, specializing in oxygen concentrator repair, cpap repair, bipap repair, liquid oxygen repair, helios repair, and more. We are a Factory Authorized Service Center for Philips Respironics, Invacare, ResMed, AirSep, DeVilbiss, Caire, SeQual, Medline, Nidek Medical, and more. We also perform Warranty Repairs for most of these manufacturers with little or no cost to you! In addition to equipment repairs, we also sell refurbished medical equipment. We carry many different models of used oxygen concentrators for sale in addition to portable oxygen concentrators. visit us at http://www.altraservice.com