1.many kinds 2.good qulity 3.good seller in the market Sensor Switch with square button:Specification of tact switch series as below,1) Temperature: -20oC65oC2) Withstand voltage: AC, 250V, 50Hz per minute3) Actuating force: 180±50gf4) Contact resistance: 50m Ω(max. and initial)5) Life: 10,000 times6) Insulation resistance: 100mΩ min. DC 250V1.2.3.4.5. Sensor Switch with square button