It's not a special model but my buddy and I both have one of these little coffee cup stirling engines. We began a fun competition to see who could get there engine to run the longest on one batch of hot water. The winning time was over 14 hours! The ticket was pre heat the thermos with boiling water, boil a second batch and refill the hot thermos, place engine and set timer. This model will self start on boiling water. The brand of thermos is Artic...a Yeti might do even longer. I believe I have well over 300 hours on this little Stirling engine. If it started to make clicking noises during an endurance run the top of the cyl is sharp glass, a light scrape of pencil lead dust falling in to the bore would cause it to go nearly silent. Fancy extra fine graphite Would likely be even better as pencil lead contains clay. The 2 little stickers on flywheel are reflecting tape, my buddy has a RPM gauge that would pick this up. We also had speed run competition
