I had two kinds of plates on my boat, the first one was called the happy troller, that was junk!! I had that one on a 140HP I/O mercuiser, than one day I was bitching about this plate and two guys pulled into the docks and they had a different style on their boats so I asked them all kinds of questions about there's and they said these are the only troll plates to buy, a little expensive but you get what you pay for, so I got what is called the easy troller, the bottom third of the plate is hinged, so if you forget to raise the plate that folds down over the prop and gun the motor to leave it gives a little instead of bending the plate or shearing off the pin that lockes the plate in place, plus they make two different sizes 30-50 hp & 50-150 I put the bigger one on it bolts to the anti-cavitation plate. At 1000 rpms my boat speed was 2.5-2.8 mph on the gps, with the plate down I was at .8mph on the gps, 1100rpm depending on the wind & waves I was at 1.25-1.50 or less. I really like it, they cost around $150.00, and you can put it on in a hour, hope this helps (I have one on my 22ft,at 900 rpm .08 on gps/355-260hp hope this helps PAP.