Help soothe and calm your new puppy with the melodic vibration of a mother’s heartbeat. The ingenious design of the Mother’s Heartbeat Heated Pet Bed by K&H creates the soothing feel and sound of a maternal heartbeat. Comes in 3 different heartbeats per minute based on breed sizes. Included with each cozy bed is a K&H Pet Bed Warmer, pillow, and heartbeat device. Heartbeat device can be installed in either the pillow or the bed. Based on estimated heartbeats of the breed of the parents and puppy. Small breed, up to 20 lbs. Medium breed, up to 80 lbs. Large breed, over 80 lbs. Also available for kittens, just look for the K&H Mother's Heartbeat Heated Kitten Pet Bed. MET listed. One year limited warranty.