This heavyweight elastic is a flat knitted elastic, also referred to as Corset or Medical elastic.  It is often seen in support belts, and offers a firm hold.  It is a non-roll elastic.  It is customary and usual for splicing to occur within the spool.

Wholesale Flat Knitted Corset Elastic 217 - Black 2". 70% Polyester and 30% Rubber. Machine wash and dry. Priced per 50 yard roll.

70% Polyester, 30% rubber

Medical grade elastic for use in back braces.  Can also be used as a decorative waistband for skirts.

80% stretch, but a firm stretch.

Non-roll (when you stretch it, the width remains 2"").