The function of a limit switch is to produce electrical signals corresponding to the position of the mechanical member to be detected.  Limit switches have operating heads which incorporate some type of lever arm or plunger mechanism; the selection of which is application dependent.  When a limit switch has positive opening of the normally closed contact (a.k.a. Direct Opening Action) it is typically suitable for use in  Machine Safety applications.

3SE03 -  North American Metal Limit Switches

3SE523. - Molded Plastic Enclosure, 31 mm width according to EN 50047            3SE524. - Molded Plastic Enclosure, 50 mm wdth

3SE511. - Metal Enclosure, 40 mm width to EN 50041          3SE512. - Metal Enclosure, 56 mm width

3SE5250 - Open Type  Limit Switches

3SE31 -  Metal Limit Switches with Molded Cable