Materials suitable for homopolymeric or copolymeric inner and/or outer covers further include, without limitation, vinyl resins comprising vinyl chloride; polyolefins such as polyethylene and ethylene methylacrylate copolymer; polyurethanes comprising polyols and polyisocyanates; polyureas; polyamides such as poly(hexamethylene adipamide) and poly(caprolactam); acrylic resins and blends thereof; b