Piston rings seal the combustion chamber. They are set with precision so as to apply the correct pressure on the cylinder wall or liner, which ensures there is a consistent film of oil across the cylinder's working surfaces. This provides sufficient lubrication and protects against wear.
Many of our kits include reagent bottles for steeping and storing bitters. This type of bottle has been used to store chemicals for at least 150 years, though the idea for the ground glass stopper dates back to the late 1700s.