Carbine Epsom Entrance Knob SetCarbine 3000 Series Epsom Entrance Knob Set Standard 70mm Backset. Function Outside function Lockable by inner push button, key unlocks both knobs but does not retract the latch. Inside function Opened by knob at all times, push button only locks outside knob. Additional Information Fire rated for 2 hours to Tyco specifications Cylindrical fixing Supplied with 70mm backset as standard with a 60mm available as an option. Display pack version is 70mm