This requires at least one adapter on each brush, rod extension, or tool piece that you use to clean inside the bore. Most of the time you need to use two adapters...one for each end of the rod. Oh, and don't lose one...you won't be able to use certain tools. I could not even figure out how to use one of them. I'm sure there was an adapter missing or something. It had two of one of them. All the pieces were there according to the list. There is quite an assortment of tools/sizes for the money. I was just affraid of losing an adapter. Just not sure would I do. I ordered this because it was such a bargain because of the number of pieces. I returned it before using. Buy only what you need.