This is a drain plug O-ring for the 290-DP, DP-E other DP drives listed below. This is one option for an MS25S Saildrive whereas the other option, part number 3855081 is a fabric gasket.
This is the Saildrive/ Sterndrive drain plug O-Ring and an oil filler O-Ring on a DP-G sterndrive.
Saildrive prop shaft sealing rings that sit behind the prop and protects the gearbox from water ingression. Two are required.
These are the 2 O-rings that sit behind the prop and protect the gearbox from water ingress. Two are required.