The Wotofo Squonk Refill Bottle is a life saver for those that squonk. No more messes just filling and installing the bottles, as those days are gone with this device. The only con is there is not a screw on tip like the Geek Vape refile bottle has. So juicing your cotton can be a trick and can get messy if you have all that flavor of juice in this refill bottle. But there is a trick, or you will be fighting gravity and your juice you just got into the bottle will siphon itself back into the refill bottle if you do not know it. You can also squeeze so hard trying to overcome the siphon that you can also force liquid out around the tube and seals of the silicone mod bottle. If this happens you will have a big mess. So to fill your bottles use this trick. Screw the refill bottle on and turn your mod upside down. Squeeze the air out of the smaller silicon mod bottle into the refill bottle while upside down. Turn it over and let off the pressure of the small bottle and start squeezing the refill bottle until it stops filling easily. Turn it over and repeat and repeat again until the bottle is filled, remembering to squeeze the mad bottle each time while upside down. That makes it so easy and all the mess it made before is gone. Now the decision to squonk and have the mess to clean up is gone. Squonking is enjoyable now so squonk away.