The width and height of rack-mounted guitar tuners is defined by internationally-agreed standards that have been in use for many years. Such equipment is often refered to as 19" Rack Mounted - the 19 inch reference is to the overall width of the rack including the mounting tabs or "ears".

The height of a rack tuner is often quoted in "U" units. Typically a rack mounted guitar tuner will be 1U, which is the minimum standard height for rack mounted equipment.

Officially a 1U "slot" is 1.75 inches (44.5 mm) tall. The actuall rack tuner willallow for a small gap above and actuallu be 1.719 inches (43.7 mm) tall. This simply allows space for the rack tuner to be installed and removed without jamming against equipment mounted in adjacent rack spaces.

So it is reasonable to assume that any rack mounted tuner of any brand from any country sill fit in the same rack case!