This is a XS Sights Sight known as the DXT Big Dot, model KB-0005S-5.
The XS DXT Big Dot night sight is the ultimate defensive sight set. Fits Kimber Micro. Precision machined in Fort Worth" TX" XS Sights feature a Big Dot Tritium front sight and express rear sight with a vertical tritium stripe for fast sight acquisition in all light conditions. Big Dot demands your attention - even in high stress. White dot reflects ambient light for best visibility in low light. Shallow V-Notch rear provides an unobstructed view of the front sight" along with a greater field of view down range" especially when moving and shooting. Day-Light" Half-Light" or Low-Light" just "dot the i" and center the dot over your target within 15 yards.
Features:
Outside Diameter Big Dot 0.188";Fits in common holsters;Tritium front and rear;White front outline front