Back Pain? Neck Pain? No Problem. The Chirp™ 4 Wheel Pack Bundle comes with everything you need to help you Feel Good so you can Do More. This bundle features four Chirp Wheels that deliver different levels of massaging relief (12" Stretch, 10" Firm, 6" Deep Tissue, & 4" Focus). This is the perfect assortment to tackle sore and tight back, leg, and even neck muscles. With Chirp's patent pending Spinal Canal you will feel allof the stretch without any painful pressure to your spine. 10 Year warranty.