I have a set of glass Wrattens that fit my series VI press on adapter, which fit most of the lenses that I use on the 4x5. They are very nice (and cheap, too!) First quality stuff!The Wratten gels are something I know nothing about other than Ansel Adams used them. The closest I've got would be Lee polyesters which fit the 8x10 lenses using a rubber band thingy. I haven't been able to find press on adapters that fit my larger lenses