Right Angle Finder - FM2n

Basically I'm looking for a Right Angle Finder for my FM2n as I shoot a lot of skateboarding with the 16mm f/2.8AIS. So rather than getting really dirty and lying on the floor, thought it'll be easier with one of these.

However there are quite a few different ones. In the FM2n manual it says use the DR-3, but there is also a DR-4.

Whats the main difference with them if any as I know that by the sounds of it the DR-4 needs an adaptor to work with the FM2n

The DR-3 is the correct unit for the FM-2 and other standard finder Nikons - F, F2, F3, FM/FA/FE series, Nikkormat...

The DR-4 is made for cameras with high-eyepoint finders: F3HP, F4, F5 ...

There are adapters to cross-mount them. Buy the one that fits the camera you use the most and use the adapter for the special cases.

So basically just stick with what the manual says then buy the sounds of it