This is the bottom end of the internal combustion engine. Three pistons move up and down in steel cylinder sleeves to turn the crank shaft. This engine, like many Honda engines, is a lightweight aluminum casting. I imagine the piston rings are thin and low tension (to reduce drag and increase mileage), and placed very close to the top of the piston (to reduce the amount of air/fuel mixture trapped between the edge of the piston and top ring that will not burn). However, this is as far as we needed to go, so we did not get to disassemble the shortblock. It will have to be a mystery until Insights start to wear out and we get to take another one apart.