This is a Sang Mao 30 amp push to reset circuit breaker.  This one includes the weatherproof boot to cover the button.  These are popular in generators. Generac part # is 075207 or 075207A. This breaker can be used in DC applications also in boats, wheelchairs, mobility scooters, and RV's.  Too many applications to list.  Sang Mao is the best in the industry.  This breaker is brand new and unused.