I’m using the Garmin Astro 320 and the T5 mini collar saves me a load of time and effort they’ve stopped making the 320 now and replaced it with the 420 the only difference is it refreshes every 2.5 seconds instead of every 5 second then there’s the alpha which is basically the 420 but it’s got a touch screen one thing I will say is if your going to invest in one don’t buy the T5 collar has they are way to big and bulky the T5 mini is way more than enough for hunting in the uk atb B.B.