These polyester ties are manufactured specifically for the rigors of missionary work thanks to our 2-year guarantee and what we learned about which ties work and which ties don't for missionaries.  Because their core and shell are polyester, they are machine washable (but we recommend hanging them to dry).  Why take polyester ties instead of silk?  Silk ties are great for businessmen, but they bleed onto white shirts in the rain and they wrinkle, warp, and fray with typical mission use.  Polyester is much nicer for missionaries and 99.9% of the people on your mission won't be able to tell that these ties aren't silk.  Plus, polyester ties are much less expensive than silk ties.