basstackle, quality injector and more, N2 manufacturing, the 9.5oz doit, bts, baitjunkys, all have the locking pins. if you are reffering to the single injector chris uses in his older videos it is a baitjunkys, which has the locking pin in the nozzle and a handle, leonard makes them sometimes still but as far as i know only seels to the members of the baitjunkys facebook group, maybe through the lureworks promotional group on facebook if they dont sell out in the baitjunkys group. the newer big barrel model he uses sometimes is a quality injector and more model, you can buy it through bait plastics, or through QIM on facebook, note their customer service is...questionable?...so do your research before you are buying, that said i have one of their injectors (a 12oz) and it works good now after getting the right orings (didnt come with the correct rings when i got it)
