CBOB's Front Sight

[Jubz]

Was breaking in a new CBOB today at an indoor range, and my front sight (stock CBOB night sight) almost fell off. Luckily I noticed it shifting off before losing it. But I see there's a pin or screw hole in the front portion of the sight and the slide.

Is this hole for a pin or a screw?
To replace, is it a standard "something" part or a DW specific part?

BTW, loved how it shot; was accurate until the front sight started shifting to the left (looking down the slide).

Tnx