These bands provide progressive resistance exercise for all of your rehabilitative and fitness needs. 99.998% FREE of soluble proteins (Latex Allergens). No messy powder. Easy to remember ROY G. BIV Progressive Resistance System. Available in prepackaged 4 foot pieces. The BodyTrends Fitness Bands come in two prepackaged sets, one for lighter resistance exercises and the other for a workout using heavier resistance. The Light pack contains: Three 4-foot pieces of Yellow, Orange and Red(thin, medium & heavy resistance) The Heavy pack contains:Three 4-foot pieces of Green, Light Blue, Navy Blue(extra heavy, special heavy & super heavy resistance) For customer service on this item, please call 800.875.6148 (9am-5pm ET M-F).