The Siemens 3SE2100-1R is a metal limit switch with snap-action contacts (1NO + 1NC) and a spring rod actuator. This model has been discontinued, and its successor is 3SE5122-0CR01.:

Enclosure: Metal

Contacts: 1NO + 1NC (snap-action)

Actuator: Spring rod

Thread Size: 1 x M20 x 1.5

Protection Class: IP67

Operating Temperature: -30°C to +85°C

Voltage Rating: 230V/500V AC-15/AC-12

Current Rating: 6A/10A

Mounting Type: Screw mounting

Explosion Protection: None

Dimensions: 118mm x 67mm x 43mm

Weight: 0.236 kg