Mercury - Thunderbolt Propeller High-Performance Series High-Polished Stainless Steel QS5005X. Overview. There's a certain confidence that settles in when you run a propeller you truly trust. You feel it the moment you push the throttle and the boat lifts cleanly, ready for whatever the day brings offshore chop, winding channels, long runs back to the marina. A prop like the Thunderbolt becomes part of that quiet peace of mind, the kind boaters only earn through time on the water. When condition