B-series uses the same housing as Final audio MAKE earphones, and the shape of the shells between B1, B2, and B3 is the same. But the finish varies with B1 (hybrid DD/BA) being stainless steel with rose gold mirror surface finish, B2 (single BA) being stainless steel with gun metallic blasted finish, and B3 (dual BA) being stainless steel with frost silver blasted finish.
The shells itself have a multi-facet faceplate surface. The inner part of the shell is rounded, while the outer part has a bit of a sharp edges. I noticed that regardless if it’s BA only or hybrid w/DD design, each shell has a pinhole vent on the inner side. The shells itself are small, have shorter nozzle with a screen guard at the top, and should have a comfortable shallow fit inside the concha area. But with smaller ears, the sharper edges of the shell did come in contact with my concha area, making them feel a bit sore. It wasn’t the end of the world, but I had to adjust the shell in my ears a few times during extended listening period.
My suggestion to Final is to make outer edges of the shell as rounded as inner edges. Also, just an editorial comment, but it’s a bit confusing with a model naming since I would expect B1 to be single BA model, B2 to be dual BA model, and perhaps B3 to be a hybrid model. But that’s not the case with B-series naming.