Z-ENDS fit over the standard bottle ends of all ZAP glues. The tips of Z-ENDS can be cut back to deposit larger amounts of glue. Sometimes glue can build up on the outside of a Z-END, let it harden and it will pop right off leaving a clean open tip. When using the Micro-Dropper tubing let the glue wick down through to the tube end, then gently squeeze the bottle to deliver a small drop of glue.