Accuracy Solutions 10.2in Picatinny Rail Black 25 Slots. It's three (3) 1.782 inches/ 45 mm long elongated slots provides ample room for scews' locations. Its two (2) round holes gives you a way to ensure that the brunt force of recoil is taken by fixed screws and not by the elongated slots. Specifications for Accuracy Solutions 10.2in Picatinny Rail: Manufacturer: Accuracy Solutions Color: Black Finish: Type III Hardcoat Anodizing Fabric/Material: 6061-T6 Aluminum Gun Rail: Picatinny Length: 10.2 in Additional Features: 25 Slots Package Contents: Accuracy Solutions 10.2in Picatinny Rail Accuracy Solutions AS-2023-10: 10.2in Picatinny Rail Black 25 Slots