I think their 6 1/4" speakers. Their the same size as the speakers in the dash.
Some 6 1/2" will fit with a bracket. Best bet is to buy through Crutchfield so that you get everything included that you will need for the install.
Crutchfield is telling me 6.5 will fit so I am going with it.... will let you know next weekend how it went
6 1/2's can fit both soundbar and dash. Had Polk Audio DXi650 put in with the bracket it comes with and sound great plus they are marine certified.