It takes a long time to wear out a Birkenstock, a favorite sandal of Boomers (with or without socks). Here's a comparison of a new pair to an old pair worn daily
Birkenstock »ARIZONA BF« Pantolette in Schuhweite schmal, mit ergonomisch geformtem Fußbett
Birkenstock mule ARIZONA NORMAL BIRKO-FLOR SCHWARZ | 2889 00022SP38