The damage formula is 0.8 * ( (Item_Level ^ 1.3) + 9 ) where the Item_Level is generally two more than the displayed level requirement base level requirements for each quality value are listed on the Manufacturers page. Gd_tunercuffs.A_Item.Item_GrenadeModulator If a grenade mod is received instead of a backpack SDU as a reward for a Claptrap Rescue mission, the Item Grade will be gd_SDU_InventorySlots.
While Grenade Mods generally always have the single Item Grade mentioned below, there are two situations in the original game where it will have a different grade:
