HI I used a simmons 400 yard works fine I can sell it for $45 shipped , I upgraded it to a leica 1600 yard unit last year , which is a great unit , The leica also does baro , angles and temp , A range finder is really helpful when hunting with airgun a they drop alot ,I have used all kinds of range finders and few will actually range what they claim , I would say the best one I ever used is called Vectronix but a unit like the Leica and Vectronics are a bit of overkill for pcp guns , It is a good tool to have . and if you want to spend a bit more go with a true range or angled one , but even an entry one like the simmons works fine for this
LOU