Anybody who regularly works on the DHLA and DRLA knows the problem of seized mixture screws.
Especially the later versions with the screws in "towers" are prone to seizing as the towers trap moisture and the bronze screws slowly seize in the Zamac carburetor body.
If you manage to remove the screws, this tap will help you to clean the thread in the body.
It will even repair slight damage.
Of course, it will not cut a thread in a completely stripped or overbored hole.
Please note that it is only suitable for the Dellorto DHLA and Dellorto DRLA versions that use mixture screws 9656 and 11068 as pictured below: