The Shield Sights Low Pro Slide Mount for Glock 21 enables you to securely mount the RMSc red dot sight without the need for slide milling. This innovative design replaces the rear iron sights with a slide-in rear sight and mounting plate, allowing for a streamlined fit with the RMSc and SMSc. The mount also accommodates standard RMS, SMS, SMS2, and Jpoint sights, although these may have a slight width overhang. Note that while the RMSw can fit, its narrower plate may not provide a complete seal. This mount is an essential upgrade for Glock 21 owners seeking enhanced accuracy and quick target acquisition. Intended Use: Ideal for competitive shooters, home defense, and range enthusiasts. Key Benefits: Easily upgrade your Glock 21 with a secure optic mount without modification. Key Features: - Securely mounts RMSc without slide milling - Replaces rear iron sights - Compatible with multiple sight models - Sleek, low-profile design Summary: Enhance your Glock 21's versatility and precision with the Shield Sights Low Pro Slide Mount, perfect for competitive shooting or everyday use.