I just picked up a Great Planes laser incidence meter. I like the expanded scale calibrated in 1/4 deg increments. However, I don't belive it will actually produce this kind of accuracy in practice. On mine, the repeatability of a measure ment is about +/- .75 deg. that is: put the meter on a solid surface and sswing the laser several times and note the readings after each attempt. The problem appears to be friction in the bearings. I've added some weight to the balance part and that helped some, I'll probably try to get some watch maker's oil and try that as well. Also, I'm not real impressed with the bracket that mounts to the prop shaft. The beam is cantilevered out from the plastic bracket and I'm not getting repeatable readings... The Robart model is harder to read and calibrated to 1/2 deg. but has better bearings and the beam can be positioned in a more balance position over the engine. The Robart one is also about $20 cheaper... In both models there is a noticable amount of "slop" in the "V" blocks that hold the beam to the wing. I don't belive that either one is truly accurate to 1/2 deg. They are still significantly better than the old "eyeball" TLAR approach. 