Press-in Bottle Adapter, 21mm. Converts a standard prescription bottle into a filling device. This plastic insert is pressed into the bottle opening. Use an oral syringe to draw liquid from the inverted bottle, then replace original cap with the insert still in place. Fits any drug manufacturer's container with a cap finish of 20mm to 21mm and an inside neck opening of 16mm to 17mm, and our #7690 2-oz plastic oval. Call for a sample to ensure it will work for your application. Non-sterile. 20 per package.