The diffuser is a hand-made, borosilicate glass cup with an inside diameter of 0.875 inches (22mm) It is recommended for DC polarity applications only and uses 25-30+ CFH of argon flow. It is rated for 180 amps on constant amperage, but can go higher with pulse settings. The diffuser is not recommended for "walking the cup" due to the nature of the glass. The Moose Knuckle 14 diffuser is recommended for welding mild steel, stainless steel, chromoly, titanium, inconel, and other space grade alloys. It works best on thinner and smaller to medium applications, such as header tubes, chassis tubing, and flat welding applications. Note. For #17, #18 or #26 size torch you will need a #17 kit. For #9 or #20 torch you will need to have a 45V44 gas lens. Keep in mind that import brands yield lower results. What's In The Box One full cup One spare diffuser Mounting o-rings