The 040-5045 is a blue cap accessory designed for Elma classic collet knobs with a 28 mm diameter, featuring a matt surface finish. This cap is part of the comprehensive accessory range for Elma's proven collet tightening system, which securely mounts knobs onto shafts. The cap is available without line configuration and is packaged in quantities of 100 pieces. It is commonly used in control panel applications and equipment requiring color-coded knob identification, providing both functional mounting support and visual distinction for operator interfaces.