Comps for 2-4 units multi family

[Tom Doherty]

BP - Doing some research on the BRRRR on 2-4 unit properties. My question is, when you request to refinance the property, what is the appraiser looking at when it comes to comps for a 2-4 unit property? Cap rate? or is it similar to residential/single family comps?

Please provide an example. 

I appreciate the help.