The safe alternative to a hot water bottle! No chance of leaks or burns from boiling water! Filled with heatable/chillable silicon beads the Heat Packs are completely odour free and can be used as a hot or cold pack. Place on aching muscles for effective relief. 40cm x 15cm. ** Heat on clean, dry plate in rotating turntable microwave ovens only. Do not allow heat pillow to come into contact with any food residue, cooking oils, grease, butter etc. Not suitable for flatbed microwaves.