Compatible with standard EIA310D 23-inch wide 2 post relay rack and 4 post server racks Converts 23" wide cabinet to accept standard 19" wide equipment 4U Height, Black Color, One end with rack screw mounting holes, other end with #10-32 threaded nuts OB slots on the cabinet side offer additional installation flexibility for rack equipment that is either slightly narrower or wider 5.5mm mounting holes located between the OB Slots are compatible with #10-32, #12-24, and M6 rack screws. #10-32 PEM nuts preinstalled on the equipment side. Supports #10-32 screw New Upgraded 14 gauge CRS steel with New Z-Shape offset design improves fit and load capacity OB Slots support #10-32, #12-24, and M6 rack screws Made in USA. Also available in 1U, 2U, 3U and 5U As technology has advanced and equipment has become more compact, the demand for wider cabinets has decreased. However, if you have an existing 23-inch wide cabinet and you want to utilize it for commonly used 19-inch rack equipment, you can achieve this by employing the RCB1060 rack reducer. The RCB1060-4U serves as the solution to modify the 23" opening, making it smaller to accommodate your new 19" rack equipment. By utilizing the RCB1060-4U, you can effectively complete your installation and ensure a proper fit for your equipment. The improved version of RCB1060-4U is designed with small to mid size networking equipment in mind. On the rack's vertical rail side, it features both 5.5mm holes and oblong slots. The oblong slots are ideal for situations where your 23 inch rack cabinet is slightly too wide or narrow, allowing you to adjust the width to match your 19” rack equipment. The 5.5mm holes provide a more secure mounting point, minimizing bracket movement under heavier loads. On the equipment side, #10-32 PEM nuts are preinstalled with standard rack spacing. These preinstalled PEM nuts help reduce installation time. For installation, one pair of RCB1060-4U is required for a 2-post relay rack, while two pairs are needed for a 4-post rack cabinet to support both the front and rear.