Weidmueller SDI SET S2.5-5.5/PH1/2

SDI SET S2.5-5.5/PH1/2 likely refers to a set of screwdrivers. "SDI" is probably the brand or product line. "SET" indicates it's a collection of tools. "S2.5-5.5" likely refers to slotted screwdriver sizes ranging from 2.5 to 5.5 (likely millimeters). "PH1/2" likely indicates Phillips head screwdriver sizes 1 and 2. Therefore, this is likely a set containing slotted screwdrivers (sizes 2.5 to 5.5) and Phillips head screwdrivers (sizes 1 and 2).