The Tommy Kono Waistband was made primarily to wear while performing waist exercises. The special type of elastic material used helps to retain body heat and give support and comfort to those whole supper aches and pains in the lower back. The Tommy Kono Waistband is one size fits all because of the velcro. The quality material is stretchable and because of the thickness, its use will give you excellent support and warmth to the area it covers. It will not "gather" or wrinkle and will outlast other when used as instructed. One size fits most.