Bought on PO #xxxxxx and part number 2556A112. Really dislike common split adjustable 1" round threading dies as opposed to solid 1" hex dies, such hex dies are hard to get in general or from this and all suppliers. Can’t figure this out in me liking them better. Re-tapping verses tapping and finishing aside in the concept of a little set screw so as to make a round die into both or neither if out of adjustment - this as opposed to buying three separate dies pre-set for the situation when needed as normal with a tap for plug, verses taper, end tap or a re-threading tap choice. Harder to install and retain with what pressure you put on them in tapping this screw in addition to those set screws for the tap handle having an effect also on the thread class tapped in retaining that round die that tends to want to rotate with the work and even get tighter with tension. Just bought a 1/8-27 round 1" die and it don’t fit into the die handle so I need to set screw it to adjust to fit a 1" die handle a lot. What’s the current thread class of fit for this factory 1" OD. set screw in fitting into a 1" die holder, and additional tension die handle adjusted die ability do do before it explodes in your hands? A 1" hex die would fit inside a 1" die handle as a given - only a question of what die in thread class I was buying. This one just to fit into the 1" die holder in adjustment exploded in my hand so as to fit into the die handle well before it attempted to screw up the threads on what I was attepting to tap. OOPS! Just broke in my hands in attempting to fit to the size of the die holder this 1" round adjustable die for 1/8-27 NPT - parts shot everywhere. 1" round die holder this die holder would fit in my rear! Expect for a high carbon steel die, that I in attempting to tension it to fit an economy grade but bought from the same store McMaster Carr die holder - it was my mistake. McMaster don’t sell much in hex dies and over the years I have been forced to buy the round tap dies say especially for this 1/8-27 NPT verses 1/8-28 BNPT die also bought that won’t also fit and is also needed for some applications of NPT verses BNPT. Expect that McMaster in being a good supplier will immediately ship out a replacement die for no charge in that it was advertised as 1" but didn’t fit into a 1" die holder (I have most of the broken parts able to return), but still a question of wasted time and this is the first time I ever broke a die. Tooth’s broken sure never a die a total dangerous parts everywhere explosion of the die. This especially if just attempting to get the thing into the handle. Not happy!!!