This tail cap is compatible with all Quark Pro and Quark Tactical lights. Please note that this part does NOT convert your Quark Pro into a Quark Tactical. A tactical head replacement is also required for a complete conversion. This tail cap only changes the way the light is turned on.
1) It has a more accessible protruding switch (cannot tail-stand)
2) it allows for momentary operation from a slight press of the button.