This is a coupling used for piping things like whipped cream. It's a convenient tool that allows you to easily change piping tips when you want to create various designs. I bought several of these because I couldn't tell the size just by looking at my piping tips, and I wanted to try them out. However, none of them fit, so I couldn't use them. The following is a description of the piping tips that are compatible: [Kougi Piping Tips] Round tips: #5 to #10, Rose tips: #3, #4 Leaf tips: #2 to #5, Double-eye tips, Single-eye tips: #2, #3 *The above sizes can be used. Also, piping tips with a base diameter of 19-25mm can be used. The photos are all that is included, such as the instruction manual. I have taken it out once and washed it, so please consider it as used. As a bonus, I will include two used piping tips. They are for flat and rose designs, but I don't know the sizes. Shipping will be compact because the diameter is 4cm.