The Schneider Electric (Square D) HLO1 Breaker Lockoff is a safety accessory designed to lock a QO or Homeline circuit breaker in the OFF position, preventing accidental re-energization during maintenance or service work. Compatible with Square D QO and Homeline single-pole and double-pole breakers. Meets OSHA lockout/tagout (LOTO) requirements. Accepts standard padlocks for secure lockout. CSA/UL Listed.