A two-part device called a coupler lets you use different decorating tips with the same bag of icing, creating several designs with the same color and consistency.
The two parts of the coupler are the base and the ring. Remove ring from coupler base. Drop the coupler base, narrow end first, into the bag and push it down as far as you can.
For Featherweight Bags: Using a pen or pencil, mark the spot on the outside where the bottom screw thread (closest to tip) is outlined against the bag material.
For Disposable Bags: Use a pair of scissors to mark a spot on the outside that is 1/4 inch BELOW the bottom screw thread.
Push the coupler base up into the bag so that you can cut an opening at the mark.
Place a decorating tip over the part of the base extending from the bag.
Put the ring over the tip and twist it on, locking the tip in place.