Covers most 120V- 277V breakers!Works on wide range of breakers, including single- and multi-pole configurationsMakes use of unique lock rail system, providing the following benefits: -Accommodates multiple locks, facilitating group lockout activity without hasps -Keeps weight off the breakers, protecting delicate electrical components from damage -Positions locks and tags outside the panel, making sure lockout activity is clearly visible to anyone in the areaTechnical Information -Lockout devices constructed of high-impact Isoplast polymers -Cables are 2 ft. in length -Lock rails made of durable isoplast polymers with acrylic adhesive backingSnap-on For use on Square DNQOand other breakers that have a hole in the switch tongue. Just align pins with hole and snap closed. Pins prevent switch from being thrownClamp-on For use on breakers that do not have a hole in the switch tongue, including multiple breakers with tie bars. Turn thumb-screw to clamp lockout securely onto switch, then snap the cover closed to prevent thumbwheel from being loosened.