You are a bit vague on what your requirements are, you would need to answer the following:
1) What distance is there between the sites, because you can get SFP in 10Km, 40Km and 80Km and other.
2) Are you using single mode/ multi-mode fibre
3) connector tye: LC/SC/ST.
Once the above is answered, then I will be able advise better.