Heat Poka Ring Size M with Cover Color: Beige No waiting to warm up! Instant! Just press for warmth! No batteries or charging required! Reusable! When you press the internal metal button until it clicks, it instantly becomes warm, so you can use it right away without waiting to warm up. It fits snugly around the neck, making it easy to move, and warms your whole body from your neck! Materials: Body / PVC, Contents: Sodium acetate solution Cover / Polyester Size: Outer diameter / approx. 16cm, Inner diameter / approx. 10.5cm, Thickness / approx. 1.8cm Heat retention temperature, time: approx. 50°C, approx. 40-60 minutes Boiling temperature, time: Water temperature approx. 70-10°C, approx. 5-10 minutes Can be heated and reused. ★Approximate number of repetitions: approx. 250 times I tried it once to see if it actually works.