Quick release - Thumb operated quick detach levers for easy removal and re-fitting to original position - no loss of zero
Saddle Height - 0.17" - 4.42mm base to bottom of ring equates to maximum scope outer objective casing diameter of 34mm if on a flat base - Most scope outer casings add 5-12mm to the lens size (depending on things like if it is an AO scope, use of flip up caps etc) so these will fit scopes approximately with lens sizes upto 20-29mm depending on the scope outer case thickness. See Clearance calculation guide below for more info on fitting thresholds.
Nikko call these low profile mounts but we would describe them as extra low height when compared to other mount rings - low are more normally around 8mm saddle height.
Extra low are rings are excellent for getting a very tight to base fit on small objective scopes or for lowering larger scopes fitted on raised bases.