The 278B Series fire alarm pull stations are for fire alarm installations in schools, hospitals, factories, and industrial locations. They are dual action devices molded from LexanÂ®. The pull stations are supplied with screw terminals for easy field wiring. The 278B Series may be semi-flush mounted using a 4-in. (102 mm) square back box, with a minimum depth of 2.25-in. (57 mm), and a single gang plaster cover. It may also be surface mounted using the Catalog No. 276B-RSB back box.