The two most popular roof materials...EPDM and TPO...were invented for use on flat roof commercial buildings and years ago adopted by the RV industry. Both are good but TPO has advantages over EPDM. TPO can be scrubbed where as EPDM should never be scrubbed....it removes material designed to protect the remaining membrane. Also TPO repairs can be done better because TPO can be fused the way plastic drain pipe is glued together giving a permenant seal. I for one have used Eternabond and will never use it again. Inspect and touch up the sealant once or twice a year and I have never had a problem...unlike with the EB tape.