The tubular latch installed in the photos is the "Premium Sprung Bolt Through Tubular Mortice Latch 64mm Black " available from Toolstation (product code 29974). This kit will work for any other Toolstation Hiatt Premium tubular latch (Toolstation codes 44688, 58386, 58911, 61612, 80028 etc).
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3d Printed Tubular Latch Jig Guide - for Smith & Locke, Union, ERA etc Latches. This jig features a short fence and smaller deck (with a removable extension) so as to not interfere with the door stop.
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Designed for a variety of deadbolts - see details below - and a variety of backsets. The 'fence' of the jig is removable. The standard fence allows for 45 and 57mm backsets; however, fences are available for bolt-through door handles with 44, 45 57mm and other backsets.
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