Footprint vs a higher-rated sibling
The 5SJ4306-8HG42: If you're looking at the 5SJ4325-8HG42 (25 A version), the physical dimensions are identical: 70 mm depth, 54 mm width, 121 mm height, same 3 MWU. It will drop into the same DIN-rail space and terminal layout. Electrically, no – this is a 6 A D-curve, not a 25 A. For a 6 A circuit you want the 5SJ4306; the 5SJ4325 is for a higher-current branch. Same frame, different rating.
Mounting & wiring notes
Degree of pollution 3, overvoltage category III – typical for fixed installations. Vibration rated 50 m/s² at 25–150 Hz and 60 m/s² at 35 Hz. Sealed and halogen/silicon-free – useful for clean-room or SIL-rated builds if the specs require. Touch protection is built in; no extra shrouds needed for the front.