The slide adapter enables depth adjustment in all of our reaction vessels. Codes -21 & -41 (complete with bushing) are designed for use with 1/4in and 1/2in horns. Extenders are also limited to 1/4in and 1/2in. Codes -25 & -45 (complete with bushing) are designed to accept our larger diameter horns and extenders (3/4 & 1 inch) and fit 36mm OD Ace-Threds like those found on our 9833, 500mL and larger vessels.