Chaco sandals are built tough and built to last. I bought my first pair of Z2's in 2002 and I still have them and they're still wearable. In fact, it was pretty annoying since new webbing colors would come into the shop and I could never justify getting them.
"Luvseat" - All Chaco footwear is built with their 'Luvseat' footbed. Designed with a contoured arch, this footbed is made to support the entire foot, so much so, that it is certified by the APMA.
Materials - All Chaco footbeds are made out of a durable polyurethane (PU) compound. Unlike most other foams, PU doesn't compress with wear. This leads to a durable, long lasting product.
Outsole - The Classic ZX2 style (that I'm wearing) has a Vibram outsole. This out sole uses Vibram TC-1 and MegaGrip compounds for performance in extreme conditions - like taking all of your children to the park.
For more information about Chaco Footwear you can visit their website: www.chacos.com.