Helmet A UIAA (Union Internationale des Associations d’Alpinisme) or CE (European Committee for Standardization) certified climbing helmet. Bicycle or ski helmets are designed for a different type of impact and will not substitute as a climbing helmet. Helmet Fit Your helmet should fit comfortably with and without a hat. It should be tight enough that it won\\\'t slide around when you move your head, but not so tight that it creates uncomfortable pressure. The helmet should sit much like a regular hat: directly on top of your head with the front just above your brow. A good fit will not allow the helmet to slide back on your head and leave your forehead exposed. Avalanche Transceiver A digital transceiver is preferred; analog will work as well. If you rent a transceiver, one set of new batteries will be provided. The Purpose of a Transceiver When climbing Rainier we will be traveling through avalanche terrain. All RMI climbers and guides wear avalanche tranceivers for safety. The transceiver is worn in its harness, over the baselayer top, but underneath all other upper body layers. We will be using the transceivers on the upper mountain and during our summit bid.