Ridgid 97080 Model 815A BSPT Self Opening British Universal Die Head. This Right Hand Die Heads Self-Opening Trigger foot Automatically retracts dies when Thread length is cut. Individual machine die heads do not include dies. Bolt Capacity 1/4 In. This Die Head is for use With Ridgid's 535-535A-1822 Machines and 300 and 300-A w/carriage.