RKX Mk4 Spotter Arca Rail & Objective Cap

The RKX Mk4 Spotter Arca Rail & Objective Cap is a purpose-built mounting and protection system specifically designed around the Leupold Mark 4 12-40×60 spotting scope. Unlike universal adapters that rely on straps, clamps, or oversized hardware, the RKX Mk4 was designed around the actual dimensions and features of the Mk4 spotter for a clean, seamless fit.

Mk4 Spotter Arca Rail

The RRS-spec Arca rail is engineered specifically for the Leupold Mk4 12-40×60. The adapter locks securely onto the spotter’s body diameter while a dedicated key-lock feature engages the base of the adapter housing to prevent unwanted rotation.

The result is a low-profile, integrated mounting solution that looks and functions like it was designed as part of the spotting scope—not added afterward.

The rail includes a 1/4-20 stainless steel securing screw and retention lanyard to keep everything secure while in the field.

Objective Lens Cap

The matching objective lens cap is purpose-built for the Mk4 housing and uses an internal tapered locking design that grips the housing securely without relying on a loose friction fit.

The cap stays securely in place during transport and field use while providing protection for the objective lens when the spotting scope is not in use.

Built for the Field

Both components are manufactured from durable composite material designed to withstand the demands of real-world field use and exposure to the elements.

The RKX Mk4 system was made for the Mk4—not adapted to it.

• Purpose-built specifically for the Leupold Mark 4 12-40×60 spotting scope
• RRS-spec Arca rail
• Locks onto the Mk4’s body diameter
• Integrated key-lock feature helps prevent rotation
• Includes 1/4-20 stainless steel securing screw
• Includes retention lanyard
• Matching objective lens cap with internal tapered locking design
• Durable composite construction
• Designed for field use and exposure to the elements
• 100% Made in the USA