XL Heating Pad (Gray) 12" x 24" by Pure Enrichment, Machine Washable #PEHT24RTG2. Heating Pads by Pure Enrichment. Details:Pure relief XL offers king-size comfort to the sore muscles in your back, legs, arms, and more. Made with plush microfibers, this deluxe heating pad provides an ultra-soft heat therapy solution for arthritic pain, muscle ache, and stiff joints. Use for just 20 minutes daily (or as recommended by your doctor) to increase blood flow and reduce pain and muscle spasms.