This Ateco 404 plastic pastry tip coupler is a two-part item to secure a pastry tip in a pastry bag. Tips can be interchangeable without emptying the content in the bag. The large coupler is used with the large pastry tips that end in the number 7, 8, or 9. This item contains one coupler base and one ring. This coupler accommodates 9/16 inch, 5/8 inch, and 11/16 inch pastry tubes and the following Ateco piping tubes: 807, 808, 809, 827, 828, 829, 847, 848, 849, 867, 868, 869.