The MPM1-21Y Mushroom Pushbutton is: Momentary - Mushroom 40 mm - Yellow - Illuminated - Chrome Plastic - No contact block This Mushroom Pushbutton is part of ABB's modular plastic range, the most versatile range with a high level of flexibility and market-leading electrical ratings. Engineered for total reliability, longer lifetime, and highest mechanical durability. Self-cleaning contacts ensure reliable operation without the need for maintenance, increasing uptime. A high degree of protection guarantees reliability in extreme environments. The innovative design simplifies the entire process, from selection to easy and quick, tool-free installation. The perfect solution for every application.