24BD16U05 up for sale is a new old stock Yugoslavia brand HSS acme  threading tap , marked 3/4-6 acme -2G , this appears to have a  roughing and finishing area built onto the tap design , this tap is 8 inches long total and has a drive shank that is 0.572 inch and the square drive is 0.426 x 0.426 in size , new tap from our surplus warehouse , see our store here on eBay we add new items weekly to our store ,thank you rwk