Smoke grenades are a third type of grenade, cut from, yet still included in the assets of S.T.A.L.K.E.R.: Shadow of Chernobyl and S.T.A.L.K.E.R.: Call of Pripyat. Simply appearing as a black and red RGD-5, and slightly lighter then the original, explosive variety.
Smoke grenade texture in Call of Pripyat
When thrown, it emits a large field of smoke which, depending on the game, has varying degrees of success. In Shadow of Chernobyl it is comparatively ineffective unless used in conjunction with a modification, whereas in Clear Sky and Call of Pripyat it can be used with a large degree of success, though most enemies and friendlies will treat the grenade as an explosive, either turning hostile or sprinting away from it depending on their disposition.