SAG MK4 S20132 Upgrade Kit for SAG MK1 Handguards

In short: SAG MK4 S20132 is the upper-and-cover upgrade set for owners of a SAG MK1 handguard. It adds the MK4 upper architecture with an integrated gas tube and detachable rear cover without replacing the existing MK1 front block.

Compatibility checkpoint

• Required existing component: compatible SAG MK1 handguard.
• Official fitment scope: all platform variants supported by the MK1 system.
• Upgrade path: MK1 handguard setup to MK4 upper architecture.
• Included interface components: upper with integrated gas tube and detachable rear cover.
• Model: S20132.

Selection rule: This is an upgrade set for an existing MK1 handguard. It is not the complete MK4 chassis; retain the compatible MK1 front section already fitted to the platform.

Purpose

S20132 lets an MK1 owner add the upper and rear elements used by the MK4 system. The resulting layout provides the forward upper interface and a detachable rear cover section while keeping the existing MK1 handguard block.

Technical specifications

What's in the box

• MK4 upper with integrated gas tube × 1
• Detachable rear cover × 1
• Required fastening components × set

Installation

Install the upper and rear cover according to the official SAG MK3/MK4 manual. Before ordering, confirm that the existing front section is a compatible SAG MK1 handguard.