It's not a gemmy item but Im not sure who makes it.
The description says that it is remote triggered or sound activated. The newer versions have an instant reset. As for the mechs, I'm guessing its just a spring trigger, with the motor attached to a notched wheel. as the wheel rotates, the notch catches the spring trigger and he pops up.
I have this. I wrapped it in plastic - under the fabric - and it worked ok the first year, but it awasn't designed to withstand any moisture at all. While stored it must have rusted. Didn't work the second year. Too bad. It was a hit the first year.
Mine is packed away in the back of a shed that is full to the doors.
As I recall, the head is attached to a long plastic "rod" that is attached to a base that is spring loaded. Rather like a large mouse trap that has a weaker spring and a stop at the verical position. It also has an electronic "voice" located in the base that screams as it rises and then says something about welcome to our graveyard or something like that.
It has red LED eyes and a crow cawing in the background sound track as it rises, so I put a crow on the headstone I placed behind it.
After wavering in the verticle position for a few seconds, a motor and gears return it to the horizontal position (cocked for the next trigger). It has a remote control or works on sound. IT DOES NOT LIKE MOISTURE.