The Garmin Splitter Cable allows you to recharge two devices at once. You can charge 2 Garmin Alpha Handhelds, or 2 Garmin Alpha TT10 collars, or 2 Garmin Alpha TT 15 collars, or a Garmin Alpha Handheld and a TT15 or TT10 collar, etc. This also works with Garmin Delta, Garmin Delta Sport, Garmin BarkLimiter Deluxe.