Slim Red Dot Laser for Byrna SD Tactical 20mm Standard Picatinny / Weaver Rail Compatible with Byrna SD / HD / Mission 4 High-quality Material: Exquisitely crafted with premium aluminum alloy. Very sturdy and durable. Compact & lightweight Picatinny 20mm standard size. Red Laser Sight Adjust to windage and elevation for day & night shooting. Anti-vibration, fog-proof, and shock-resistant.