The wpn_sig550.dds file you have requested: Shadow of Chernobyl / Skins / Weapons / SIG550 - 1000kb is not available. Perhaps try browsing all files for the game S.T.A.L.K.E.R. Shadow of Chernobyl and upload any files you want to share or are missing. This is the only information we could locate:
This is a modified skin for the Sig550. It's been give a make over with some blue variations and several things have been removed from the sight.