The Oxford/Sure-Seal™ Valve Cap
1. Remove the plastic overcap, A, from the Sure/Seal bottle, B. 2. Slip O-ring, C (supplied with the Oxford valve), firmly over the metal crown cap until it sits on top of the glass lip of the Sure/Seal bottle. 3. Securely screw the Oxford Sure/Seal Valve Cap, D, on top of the bottle, B, until it sits tightly against O-ring. Diagram 2. 4.