Use it to form new threads, re-form burred threads or clean out plaster obstructions. Rethreads to next larger size if threads are stripped. No. 627-20. Tap Sizes 1/4-20, 12-24, 10-24.
I've been looking to buy one for years. They were no longer available through Klein. And one day, it just dawned on me to look on EBAY. I found it immediately. Looks to be really well made and it turned a useless tool into something I can get something out of again. It's been laying in my toolbox for years unusable.