For the first Fermi SNR Catalog, a simple model which includes radio and GeV-TeV data has been developed. Starting from particle injections described with broken power laws, the aim of the model is to describe the broad band spectra of the detected SNRs of the first Fermi SNR catalog. Particular attention will be taken to the estimate of the efficiency of the acceleration processes, the role of the environment in the production of the observed GeV gamma-ray emission, as well as the evaluation of the electron to proton ratio on a case by case basis.