These are the original and the best of the modern wheel type marking gauges is made by Glen Drake Toolworks in northern California.
The fine adjustment and the finesse with which it functions is one of the stand out features of this quality tool.
Available in three sizes:
The Tite Mark Mini - 100mm or 4" marking width and 38mm dia head. 1/4" rod diameter.
Tite Mark - 120mm or 4.5" marking width and 40mm dia head. 5/16" rod diameter.
Tite Mark Long - 170mm or 6.5" marking width with 40mm dia head. 5/16" rod diameter.
Be aware of the different bar diameters when purchasing spares or accessories. The mortise blades and all other blades are designed to fit the larger two gauges, NOT the mini.
So if you want a small precision marking gauge and have no desire to kit up with other blades then the Mini is perfect for you.
If you want the option to kit up now or later then you need to get the TiteMark regular or Long version and all the accessories will fit at any time in the future.