I have a Competitive Edge Dynamics, $200 and it's very accurate, repeatable, when its working. They are all sensitive to light & clouds, and shadows from trees, ect. Some days it works fine, then the sun changes or it gets cloudy out and she no workey. Another thing to remember is when shooting magnums, any caliber that has a blast shockwave will set the thing into fault. For me that's my 30-378 mag, ect. You have to make a blast board or plastic shield with a 2 inch hole in the middle. Set board in line with target about 10-15 feet from T-bench; you shoot bullet through the 2 inch hole on the way to the target. Ha, You'd think your friends would miss the hole and put holes in board, but the only friends that have done that off my back porch bench is the local Indians, ha ha and I never let them live it down. I'd buy the CED model again unless I could afford that $500 one made in Texas; and I can't ha ha. I hear that 500 dollar model is the ticket just the same. I got a pict of mine somewhere, will try to post.