Krypton gas is characterized as an inert, odorless, colorless, tasteless, non-toxic gas which is about 12 times more dense than air. It is used to replace air between the glass panes to reduce temperature transfer and deter convection.

-see also:
"Krypton gas" is in the UNSPSC Code "12142003"
  Krypton gas Kr
Ref: 124356/2006-10-19