An avalanche beacon is an absolute necessity in the backcountry. As soon as you leave the trailhead or leave the resort boundary, you and everyone in your group should be transmitting (wearing a beacon and have it turned on). No matter which one you choose, practice with your beacon until its operation is second nature and you’re sure you can use it under the worst stress of your life.
The more range a beacon has, the more likely that it will be able to receive a signal early in the search process.
Multiple Signals & Marking:
Some advanced beacons allow you to mark multiple burial victims or automatically guide you to the closest signal, blocking out all others, to drastically reduce search time in the event of a multiple burial.
Two or three antenna beacons have quickly become the norm due to their improved distance and directional sensitivity; the three-antenna design is a further improvement that helps to reduce signal spikes when doing close, precise searches.