Master Model from Poland specializes in metal turned parts for aftermarket kits. In my personal option they are among the best in the market. I really like their products.
This set is devoted to the HMS Belfast and it includes a set of 12 replacement metal barrels for the 6-in guns and a set of 12 replacement metal barrels for the 4-in guns. The parts are very nicely detailed down to the holes on the end of the barrels. It also includes resin correction parts for the 6-in mountings, including some metal pins to keep the parts in place and to allow variable elevation of the guns.
I have to apologize for not being able to get good pictures of all the parts. They are so diminutive that my camera was not able to focus on them. I have included some screen captures from the manufacturer website in this review.