Don-Jo CP-258 Hole Conversion Plate | Cylindrical to Rim Cylinder Adapter

The Don-Jo CP-258 Hole Conversion Plate is a specialized hardware adapter designed to facilitate high-security hardware transitions on commercial doors. This 2-5/8" diameter conversion plate allows you to transform a standard 2-1/8" cylindrical lock prep into a precision 1-1/4" cylinder hole. It is the primary solution for rim cylinder conversion, enabling the installation of exit device trim or specialized key cylinders into a pre-existing bore without the need for door replacement.

By reducing the aperture of the door’s face hole, the CP-258 provides a stable, secure mounting surface for the new hardware. It is a critical component for commercial door retrofitting in schools, retail centers, and industrial facilities where upgrading to an exit device or a rim-cylinder-based system is required.

Key Features & Performance

• Specialized Hardware Adaptation: Precision-engineered to convert a 2-1/8" bore to a 1-1/4" hole, making it compatible with standard commercial rim cylinders and mortise cylinders.
  
• Rim Cylinder Security: Provides a reinforced, rigid foundation that prevents the cylinder from shifting or "spinning" within the oversized original hole.
  
• Sized for Coverage: The 2-5/8" diameter ensures that the plate completely covers the original 2-1/8" cutout, hiding any "scarring" or finish wear from previous lock roses.
• Heavy-Duty Steel Build: Manufactured from high-strength steel to ensure a permanent, tamper-resistant fit that maintains the structural integrity of the door face.
  
• Paint-Ready Grey Primer: Supplied in a professional grey primer finish, allowing for immediate on-site painting to match the door’s existing color.

Technical Details & Specifications

• Brand: Don-Jo
• Model Number: CP-258
• Diameter: 2-5/8" (Single Side Only)
  
• Inner Hole Diameter: 1-1/4" (Standard Cylinder Size)
• Material: Durable Steel
• Finish: Grey Primer (PC)
• Installation: Designed to be used on one side of the door. For high-vibration or high-security areas, this plate can be installed using thru bolts or internal mounting screws depending on the cylinder type.

Why Choose the Don-Jo CP-258?

The Don-Jo CP-258 is an essential tool for locksmiths and facility managers tasked with commercial door lock upgrades. Moving from a standard lever set to an exit device often requires a rim cylinder, but the existing door prep is usually too large to support it. This cylinder conversion plate bridges that gap, offering a professional, "factory-finished" look and a secure fit. It is a cost-effective, permanent solution for door hole reduction, ensuring your high-security hardware performs exactly as intended.

​