The XS Big Dots I bought for my Shield do not fit right in the gun, the fs is too tight(even after much fitting) and the rs is too loose. Plus, I was not at all happy when I realized they were not "full" night sights. The sights were purchased through Amazon, I checked the description several times and it said nothing about the rs not being "lit". The company that sold them actually started giving me some difficulty about returning them
After some back & forth they finally did give an RMA and refund.
I'm waiting on TruGlo TFOs as a replacement.