Master Model from Poland specializes in aftermarket turned-metal parts for model kits. In my personal option, they are among the best in the market; I really like their products.
This set is devoted to the German 2 cm L/65 Flak 38 and includes a turned-metal barrel and a flash suppressor. The set is very nicely detailed, capturing small details, even down to the holes on the side of the suppressor.
The instruction sheet clearly describes where to cut and how to modify the plastic part to receive the aftermarket detail part. It is a very easy task, and any modeler with a bit of experience modifying parts will run into no problems.
My sample suffered some minor damage during transit. However, it was easy to shape the flash suppressor back to its original size. I just used the tip of a toothpick and very gently rolled the piece back and forth until it rolled smoothly over a flat tile (any hard, flat surface would work).