Free: Contests & Raffles.
I would steer guys away from and drop compensating turret (one exception would be varmint hunting when speed is more important than a perfectly placed shot). They are calibrated for a given load at a given altitude and given atmospheric condition. In their advertising they say it's based on your "average" temp, "average" elevation, etc. If we're just "averaging" all these important factors, we can just as easily "average" ourselves into an all out miss or at least a poorly placed shot.I will develop a load for my rifle and run that same load through, until I've literally ruined the barrel. I use drop charts... and just like a custom knob my chart is calibrated for a given conditon/elevation/temp etc.... well over the life of that rifle I will print myself probably over 50 different drop charts for different hunting trips, or shooting matches etc. I would say that unless you want to order 50 different knobs.... stick with standard MOA or Mil turrets and print yourself CONFIRMED drop charts for your various outings with your rifle. Many barrels will increase muzzle velocity around 150 rounds and MV's can fall off some as throat erosion changes the pressure curve.... again you would have to get new knobs (turrets/dials). If you are simply after an "easy" way to shoot long range and don't care to go through the work involved in testing and calibrating your charts to match actual drops, you probably shouldn't shoot far enough that you would have to hold over or dial a knob anyway. JMHO
Its just a dial calibrated to your load.