This product is a replacement top cap w/ the drip tip mouthpiece for the Kangertech Protank 2 and Protank 3 2.5ml BCC. This product is the piece that is directly above the glass that includes the center tube and drip tip. This product connects by screwing the lower connector (sold separately) on the center tube to hold the glass in place.
It is simply a replacement part to be used if your protank piece has been lost or damaged. It cannot be used without the remainder of the protank pieces found below: