Product Name: Push Button Switch LED color: White,Yellow,Red,Green,BlueRound : Flat round Operation Type: Momentary type (push it-on, release it-off) and amp;Self-locking type Hole Size: 12mm、16mm、19mm、22mmNote: Package Includes: 1 x LED Button Switch 1.We provide clear pictures, measurements where possible. Please check as much as possible to make sure the item is the one that you need. 2.Please allow 0.5-1 inch difference due to manual measurement.(1inch=2.54cm) 3.There Are No Instructions Included In This Kit.Professional Installation Is Highly Recommended!Advantage: High-grade appearance and nice touch feeling.Adopt rubber ring and hexagonal nut fixed, anti dust and waterproof, which make it great for outdoors use.Copper plating silver terminals for good conductive properties.1.What does the signal “NC” and “NO” means?”A” “+”: positive pole of the led”LED” ” – “: negative pole of the led” NC “: Normal Close” NO “: Normal Open” C ” : Common2.How to connect?1.Connect ” NO ” and ” C ” : The circuit is alway open unless press the button.2.Connect ” NC ” and ” C ” : The circuit is alway close unless press the button.