Although many designs of quick-set tool holder have been produced, the best known (and best quality are the British  "Dickson" shown above with its dovetail clamping system, the American "Aloris" piston type and the three from Switzerland: the Tripan, Multiquick and famous Multifix.
Using high quality steel, the Dickson is hardened and ground, finished to very close tolerances and produced in a variety of sizes to suit lathes from 89 mm (3.5-inch) to above 381 mm  (15-inch) centre height. Ordinary and extra-long toolholders to take standard, parting, boring and Morse taper bits are available and, once mounted in place on the central block, can be quickly adjusted in height until the best cutting effect is found and the setting locked. This completely obviates the need to fiddle with packing pieces and, if kept together, the holder and tool can now be guaranteed to drop back into exactly the same position every time they are used. It is strongly recommended that, in order to get the best from the assembly, a selection of extra holders is acquired so that each commonly-used tool can be given its own and left in place.
While the larger sizes are largely immune to heavy handling the three smaller models should be treated with care: it is not necessary to brutally yank up the adjustment and retaining screws; instead, just firm hand pressure will lock the units securely against the heaviest work. Full details of the Models and their measurements can  be found below.
Spares for these units are available.
These toolposts have been widely copied in India and China - using inferior materials and indifferent standard of fit. You might be lucky and find a perfect example but amongst other faults reported are clamping pins that snap off, bases that are not flat, V-grooves out of parallel and toolholders that fail to contact fully with the guides and wobble about..