The Schneider Electric A9L16311 is a Type 2 surge protection cartridge from the Acti9 iQuick PRD range, rated for 20 kA max discharge and 5 kA nominal discharge on a 230 V AC 50 Hz network. The MOV-based design clamps at <1.2 kV protection level, with a <25 ns response time — fast enough to catch switching transients before they reach downstream electronics. This is the replaceable cartridge (C20-350) for the iQuick PRD20r base, not the complete SPD. The plug-in mounting means you swap the cartridge without pulling the base wiring — useful for panel access and periodic replacement after a heavy surge event. The white/red flag gives local visual status.
Type 2 (Class II) per IEC 61643-1 / EN 61643-11 means it's sized for the main distribution board — handling induced lightning surges and switching overvoltages, not direct strikes. The 20 kA max discharge (Imax) is the single-pulse survival limit; the 5 kA nominal (In) is the repeated-duty rating for coordination studies. The 350 V MCOV (Uc) matches 230/400 V TN or TT systems, and the <1.2 kV protection level (Up) keeps let-through voltage under typical equipment impulse withstand (2.5 kV for basic insulation). The 12 mm width per pole (1.3 x 9 mm pitches) fits standard Acti9 DIN-rail spacing. Depth is 57 mm, height 50 mm.