High Quality -- Made of stainless steel material,more solid and last longer,heavy duty and perfect polishing make it used for longer and easier than ever to carbonate your beverages Cost-effective Carbonation Tool -- Use it to counter pressure bottle fill PET bottles,gas (grey) ball lock connectors, or liquid (black) ball lock connectors,more portable, convenient and cheaper than CO2 systems Used Easily -- Attaches to plastic bottles and connects to a gas side ball-lock disconnect in order to inject CO2 into the bottle, creating carbonationyour beer is available to drink almost immediately. Various Usage -- Carbonation caps can carbonate a number of beverages, including beer, soda, water, and juice,also can clean your beer line and to counter pressure bottle fill PET bottles 100% satisfaction guarantee -- ProMaker high quality Carbonation Cap equiped with extra 4 o-rings in a small bag,in case that the o-ring abrased after for a long use lead to leak,then you just need replace a new o-ring instead of buying new Carbonation Cap.If not satisfied,just return it and get your money back