I have had 2 of these and neither have worked. I just did an ONR wash and have the Pro-Blend attached on a 128 oz bottle. I squeeze 2 oz into the chamber and let the rest drain back down into the bottle. I turn to pour (without squeezing) and the rest of the bottle continues to pour out the same drain hole. I guess I could unscrew it each time I have my desired quantity. I told AG of the problem a long time ago and they sent a replacement. Same problem. Is the pressure of the 128 oz too great for it to handle?