Landis Teledyne 2" capacity. The shank OD 2.750 the ID 2"+ That means you can thread 2"Diam. material thru.I have couple sets of chasers 1"- 5 TPI that I used to make 25" long jack screws for a customer twenty plus years ago.I used a J&L#5 turret lathe. The head comes with the original instruction book. Thanks for reading!