GregTech is an add-on to IndustrialCraft2. In Feed the Beast, it adds compatibility to many other mods. GregTech adds a great deal of complexity and depth to Industrial Craft. Gregtech is one of the most controversial mods in Feed the Beast; much of the playerbase is polarized over whether or not to include it, with supporters claiming that it provides well fleshed-out endgame content and opponents arguing that the recipes are prohibitively expensive. Gregtech may have a hard learning curve for people who are already used to playing Industrial Craft, as it changes many IndustrialCraft recipes if set to its default configuration; one can however disable these expensive recipes by editing the GregTech configuration files while maintaining the benefit of the added content. Playing with the expensive versions of recipes enabled can be a major hindrance to people starting out on a game, however, it adds many useful items like fusion reactors, iridium reinforced tungsten blocks (impervious to a nuclear blast), more fuels and cooling options for nuclear reactors, additional generators, an advanced grinder that give more items per ore than an ordinary macerator, improved interoperability between other mods and IndustrialCraft, and more.