I am going to have to qualify having installed both Earl's and Meprolights on P99s. Earl's are far easier and more consistent in terms of ease of installing. They (Earl's) require no fitting (none of them), just slide the rear in. And that's why I much prefer Earl's despite the additional cost. 'Seems like tolerances vary on the Meprolight rear. You might get lucky and then again you might not in which case you are going to have to do some fitting. If you want to install your sights yourself but have never fit dovetail sights before (and don't want to learn ), I really think Earl's are the way to go. But that's just me.