First Alert SMI100 Battery-Operated Smoke Alarm Size:1.9 in H x 5.4 in L x 5.4 in W 1-1/2" female pipe thread

1-1/2" female pipe thread

Diffuse acrylic lens providing a single smooth line of light shaped to resemble a fluorescent tube

middle and index finger

Built-in wire channel keeps wire centered

First Alert SMI100 Battery-Operated Smoke Alarm Size:1.9 in H x 5.4 in L x 5.4 in W 1-1/2" female pipe threadThe First Alert SMI100 Battery Operated Smoke Alarm is available in a convenient two pack. The SMI100 smoke detector is equipped with First Alert's Precision Detection advanced sensing technology and meets new industry standards. This battery operated alarm is easy to install and the front access battery compartment makes for easy battery replacements. First Alert's Precision Detection advanced sensing technology complies with new industry standards