Stalcraft Wiki: MIS-113 Iolite

In-game description (EXBO)

Like other suits in Research Institute 7's scientific series, the Iolite is designed specifically for protection against the particular threat of high radiation levels. Although radiation is one of the most common hazards in the Zone, many stalkers consider this suit a hard sell, as most gear in the Zone already offers adequate radiation resistance on its own, without sacrificing protection against more immediate threats.

Quoted from the game's own text in EXBO's public game data. Not written by STALCRAFT Meta.