Tennis Radar Guns Speed Sensors (Hands-Free) - Measure Serve, Racquet & Ball Speed, High Tech Gadget & Gear for Tennis Players, Black (NIS022132026)

I was eager to get this because it has a large front-display, is real radar, and is inexpensive. However, I was very disappointed with it and considering returning it to Amazon. Based on years of ZEPP racket sensor data, comparable serves tracked with excellent radar in pro TV matches, and related YouTube videos the mph readings of my serves when the device is positioned at the net according to instructions were falling around 30 mph short. After studying some more videos on YouTube, it seemed there was at least a partial cause: pro radar trackers are looking at the ball just after leaping off the strings while the ball slows by friction with the air arriving at the net (???). Another reviewer on this page saw the same thing as me. I then tested the Net Playz device by placing it on ladder rungs a few feet in front of my serves, at different heights. I started getting reasonable readings, elated! But then I realized after having turned it off, I’d forgotten to switch from kph to mph. This gave me an idea! Leaving it set on kph I put it back at the net and the raw numbers were what I’d expect from my historical mph experience: 2nd serve with more topspin in the 80’s and 90’s… first serve with minimal topspin at or a bit above 100. I was also seeing the occasional even-faster first serves! Others might not want to do this, but since I’m just getting readings for my own fun and improvement (not instructing others) I’ll just use it on kph which bumps up the too-slow net-level mph into the expected range. Probably it’s not totally accurate, maybe even cheating a bit high, but I think it’s an approximation of the raw number speed the ball is at when leaping off my racket. The device certainly seems to differentiate different types of serves well if it is aligned properly: as high as possible with proper tilt straight at the arriving ball (if off, the numbers drop). Apparently to get highly accurate mph numbers at the racket contact one needs a pro-level system which costs up to thousands of dollars. Not wanting to spend that much, my cheating leaving-on-kph pseudo-mph “fix” will serve me just fine (close enough). Hope my experience is helpful to others wanting inexpensive radar scrutinizing their tennis serves and strokes!p.s. In further consideration of the puzzling slow mph problem for tennis balls, I'm thinking it may be due to this machine apparently being designed primarily to use with baseballs. Those are a different size and constituency than soft tennis balls. I saw that another reviewer noted that this machine doesn't work on ping pong balls, emphasizing the machine's variable ability to properly read different balls. I've used this now for several weeks in the way I suggested above and am very satisfied. Pretending that the kph numbers are true mph values for tennis balls gives me very believable numbers on my serve and groundstrokes. As such I have it sitting in place behind the net, flicking to "on" whenever I want readings while clicking it off to conserve the batteries when not needed. With my "adjustment" this is a wonderful gadget! What fun to get immediate, easily viewed large "mph" readings whenever I want!

I ordered the gun on Friday and it arrived on Sunday. I was able to put batteries in it and attach the tripod. I took it to the tennis courts and was able to track my serve speed and my racket speed.

Happy with the product Works like charm

The accuracy wavers so many readings have to be ignored. The volume is set too low for the distance it is from the servers and there is no volume adjustment. On the bright side, it’s easy to read and set up.

Speed displayed will be lower due to "cosine effect" as the manual states, so you need to position the device as close to your target as possible. In tennis, I use a telescope-tripod at level with the top of the net. The vertical angle of the device also needs to be adjusted to match the angle of the incoming ball. Also, ideally adjust the xy axis angle depending if you're serving to deuce or ad-side. I saw it's now on sale for 60 bucks, so great deal. i paid 70.

Not accurate. 30 + mph slow