Product Description - UniqueFire Snap in Rail Adapters Converts 11mm Dovetail to 20mm Weaver Picatinny Converter Mount (D0017(2PCS)) - Top Slot w/Spring Tension Retraction/Expansion Design to Snap into Picatinny/Weaver Base, Description: Length: 1 " Width: 0.93 " Height: 0.24 " Weight: 0.18 oz Color: Black Material: aluminum Rail Type: 20mm Picatinny / Weaver Characteristics: Extremely low and lightweight profile Accuracy and reproducible alignment Easy installation with most .22 / rails Detachable locking pin for secure installation.Innovative rail platform to convert most .22 / rails Upper slot with spring tension retraction / expansion design to snap into the Picatinny / Weaver base Package: 2 Pair/Set (The set includes two piece of adapter and two piece of wrench.) Easy to install. Help you to convert the 20mm bottom to the 11mm buttom Removable Stop Pin Rail Installation with Stop Pin Holes Rail Installation without Stop Pin Holes Lifetime After-sales Services: We provide Lifetime After-sales Services. If the product you received has any defects or is not satisfied. You can choose to replace it with a brand new knife or request a full refund. If you have any other questions, please feel free to contact us.