I bought one of those swing speed radar things when I got back into golf a few years back because the fella who was building my Wishon clubs needed to know my swing speed. He was a couple states away, and I had no where close by to have my speed and tempo checked. It ended up working out so well with the 870 irons, that I ended up buying 2 fairways, 2 hybrids, 3 wedges, and 2 drivers from him. Unfortunately (for me), he's no longer in business due to retirement (good for him). I have since upgraded to a Skytrak unit, which is waaaaaayyyyyyy better. I use it in my garage with Qolf balls when weather permits. It's pretty accurate, imo. I may upgrade to the game improvement mode this fall just to keep it interesting. For those who don't know, SkyTrak comes with a driving range, and it gives you data like carry and total distance, side spin, back spin, dispersion, and a couple other things. By upgrading to the game improvement mode, I'll also get a long drive challenge, closest to the pin challenge, and a host of other things like a 9 hole short game challenge and environmental controls, where you can dial in correct distances for your area with humidity and altitude controls. Occasionally, I take it to the range to compare, but it's a pain dragging it along with an IPad and golf bag.