This is a XS Sights Sight known as the Big Dot Tritium Front, model CK-0001S-5.
The XS DXT Big Dot night sight is the ultimate defensive sight set. Fits Canik TP9SF" TP9SF Elite" & TP9SFx. 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 and for those with poor eyesight" aids in rapidly achieving combat effective hits. 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. Outside Diameter Big Dot 0.188"; fits in common holsters. Installation might require filing to fit sight to dovetail" do not use a sight press/pusher tool.
Features:
Green tritium .188 wide with white outline front
Express rear with vertical tritium stripe
Fits Canik TP9SF