It consists of an adjustable compressor and a bubble overlay with flaps. This is an alternate pressure system for preventing decubitus ulcers. There are 2 hooks to secure the compressor to the bed's foot end. The overlay is made of PVC with bubbles on its surface that are blown up every 10 minutes on an alternate cycle. This provides a constant massage that prevents pressure ulcers and helps blood circulation. Suitable for patients weighing up to 120 kg.