5characters... I got this response from and FSWerksVP on focaljet... This is the only difference aside from what is stated on the site but do let me know how it turns out either way...
Originally Posted by FSWerksVP
They both work great. The Green filter is a different design and costs us less so we charge less than our ITG filter. The ITG air filter is a bit easier to clean.
Some people really just prefer one design over the other so we're giving you the choice. :)