I spent part of yesterday on a dive boat watching DSMBs signalling divers doing decompression. They were using very big ones, and they were either bright yellow or orange. In my opinion, the yellow one was easier to see. The seas were a little rough, so having the high visibility was a plus.
What you want in a DSMB really depends upon the kind of diving you are going to do. The smaller ones are much easier to inflate and carry, and the larger ones are easier to see on the surface. If you are deploying it from depth, it is easier to fill because you don't need to get as much air in it to get the job done (because of expansion as it rises). There are a lot of choices, so give it some thought.
http://www.diverightinscuba.com/liftbagssmb-c-46.html
What you want in a DSMB really depends upon the kind of diving you are going to do. The smaller ones are much easier to inflate and carry, and the larger ones are easier to see on the surface. If you are deploying it from depth, it is easier to fill because you don't need to get as much air in it to get the job done (because of expansion as it rises). There are a lot of choices, so give it some thought.
http://www.diverightinscuba.com/liftbagssmb-c-46.html