Master Series Stanley vs. Classic Stanley Thermoses Ultimate Endurance Test

I have previously tested Made in USA classic Stanleys against Made in China classic Stanleys (https://youtu.be/QvvITJdVSUM). You can see the results in that video or in its description if you don't want to sit through the whole thing. In this video I took the best-performing Stanleys and pitted them against Stanley's new (Made in China) Master Series which is supposed to keep liquid hot up to 40 hours and have new "quad-vac" technology instead of just the traditional double wall vacuum insulation. Here are the results of four flasks of 203-deg. F. water left in mostly single-digit temps for 30 hours: 1980 (made in US and best performer of previous test): 122.4 deg. 1998 (made in US and not previously tested): 74.5 deg. 2016 (Made in China): 112.7 deg. 2018 Master Series (Made in China): 125.4 deg.