Yes, this will work great with the Glock 19 Gen 3!
Per Crimson Trace: To select desired Mode, press both activation buttons at the same time for 3 seconds to cycle through the modes; release buttons at desired mode. When changing between Constant On and Momentary modes, a slight pulse will occur indicating mode change.
The Crimson Trace Rail Master Universal Tactical Light mounts to picatinny accessory rails. So yes it will mount to the accessory rail on the SAR 9mm.
Yes. The Crimson Trace Rail Master Universal Tactical Light will fit your M9A3. It is compatible with most pistols, rifles, and shotguns with M1913 Picatinny (or similar) accessory rail measuring at least 1" from recoil lug to trigger guard.
Yes, this will fit the S&W M&P 2.0 Compact.
Yes, this will fit the rail of the CZ P10f.
No, this will not fit the Shield 45 or Shield 9 since they don't have an accessory rail.
Yes, this light will fit that pistol.
Yes, this light will fit that firearm.
The CMR-209 will fit as long as long as it measures at least 1" from the recoil lug to the trigger guard for the accessory rail.