i've been wearing a t-shirt for over 20 years now and it's still in great shape

Most of the time my t-shirts degrade in like 5-10 years, start getting holes, get too thin, stretched out, etc. I have one t-shirt though that I wear moderately regularly that's still going strong after 20. It wasn't high quality or expensive or anything I have no idea what the deal is. I got it for "free" at a football camp I went to in high school. It doesn't have any holes, it's probably thinned out but not too bad, and the collar or anywhere else hasn't stretched out at all. I don't know what sort of technology was used to create this super shirt but I wish I could find out and have all my shirts last this long.