ERGO M-LOK to Picatinny Mounting Platform. Each takes up one M-LOK slot. Stackable design allows you add multiple of these side by side to create a continuous picatinny rail. The outside is a Picatinny rail. The inside is the mounting system to the M-LOK handguard. Hard anodized finish on 6061 T6 Aluminum Specifications for ERGO M-LOK to Picatinny Mounting Platforms: Manufacturer: ERGO Color: Black Finish: Hard Anodized Fabric/Material: 6061-T6 Aluminum Gun Rail: Picatinny Condition: New Quantity: 1 Features of ERGO M-LOK to Picatinny Mounting Platforms: Low Profile 2 Mounting Holes M-LOK 4 Slot Picatinny Rail Hard anodized finish on 6061 T6 Aluminum Package Contents: ERGO M-LOK to Picatinny Mounting Platforms ERGO 4251-(B): M-LOK to Picatinny Mounting Platform