UTG PRO SD Monolithic M-LOK Forearm Add-on, for MP5, Type III Class 2 Matte Black Anodized 6061-T6 Aluminum, Extended Forearm Compatible with Most K-Length Suppressors and up, Two-inch Inner Diameter Provides Necessary Clearance for M-LOK Hardware to Clear Most Suppressors Mounted Standalone or Wrapped, Requires UTG Pro Monolithic M-LOK Handguard (MTU055SSM), Steel Hardware Included. Proudly Designed and Made in USA Extended 4.2" cylindrical forearm compatible with most K-length suppressors and up Two-inch inner diameter provides the necessary space required for M-LOK hardware to clear most bare or wrapped suppressors and improves heat dissipation Provides an improved handhold and additional M-LOK real estate Compatible with and requires the UTG Pro Monolithic M-LOK handguard (MTU055SSM) for the MP5 and similar clones Counts as one 922(r) compliant part