My Poulan string trimmer needed a carburetor adjustment. The screws are knurled, recessed, headless things requiring a special tool. Even on eBay they charge $40 for what is basically a cheap screwdriver.This thing allowed me to make the adjustment. Honestly it didn't print very well, the splines inside are too small to print on my Prusa, so basically I printed a plastic cylinder that meshed with the screw splines well enough. I am leaving the splines in the scad in case someone wants to print this in metal on Shapeways or something, though I would tweak the file a bit before doing that, I think the ID might need to be reduced a bit first and a little taper might be called for. Also if I was getting it printed, I'd probably double the length of the hex shaft - I kept it short here for strength but it's so short that I wound up using pliers to push it in and turn it.In any case this was good enough to give my weed trimmer carburetor's low speed jet the 1/2 turn it needed to run properly.