Generic cockpit seat armrest covers for most 727's and 737's.  Many airlines routinely use these rather than maintain the expensive leather armrests on their planes.  That's great for us because we then can sell seats with beautiful armrests by just removing these covers.  It also gives us a huge pile of covers that can be sold at a low price should your armrests look crappy.  They slide on, and fasten with velcro in 30 seconds.
 
$35/pair