First used in the Curzon Road Hostels in Delhi in 1967, the pullblock is a single unit, easy to manufacture, cheap, combine of lockable bolt and door handle which could be fitted left or right and on which you could use your own lock.

1963 blueprints by Habib Rahman for the Pullblock, the prototypes are from around 1966.
1963 blueprints by Habib Rahman for the Pullblock, the prototypes are from around 1966. © Ram Rahman