What Ronin said...

These are pretty great for the price: Ameriglo Tall Suppress 3Dot Tritium For Glock

These are also a good deal: TRUGLO Tritium Pro Glow-in-The-Dark Handgun Night Sights for Glock Pistols

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Both will work with your g19 slide, and are solid choices, even more so for their price point ($70). Free shipping if you have Amazon Prime.