Mercruiser Sterndrive Outdrive Gasket set.
Fits: R, MR, Alpha I, Alpha Gen II (1983-Newer)
Replaces Mercruiser PN. 27-64818A3 & 27-94996Q2
If you prefer the OEM Mercury gasket set, you can find it here.
Replace it every time you remove your drive, which should be every year.
And don't forget to grease your driveshaft splines with Quicksilver Extreme Grease.
If you want to see a video on how to remove and replace your sterndrive, we have one on our Youtube channel.