BudsGunShop.com - Remind me what the FS means?

FS is for fixed sights, Glock uses FRT for front serrations. Hope this helps.

Craig, Fixed Sights. Have a great day!

I have seen where it is claimed to be Fixed sight or Front serrations but nowhere has glock stated what it is in this case the gun has both fixed sight and front serrations

Front serrations, its the textured ridges on the front of the slide to help get better grip if you hands are wet, or covered in mud, blood or whatever. Standard glocks have a smooth front of slide.

Fixed sights, Glock's way of saying their non-adjustable plastic sights that are standard to most models.