This is a Sang Mao 30 amp push to reset circuit breaker.  These are popular in generators and this is also Generac part # 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.

This also is a good replacement for  MPN# 0H0265E

that fits 
5940-0 (GP6500) Portable Generator
5943-0 (GP7500E) Portable Generator
005796-1 (XG6500) Portable Generator
005798-0 (XG7000E) Portable Generator
005747-0 (XG8000E) Portable Generator
005802-0 (XG10000E) Portable Generator
005930-1 (XP6500E) Portable Generator
005932-0 (XP10000E) Portable Generator