The Schneider Electric DF2LA1801 is a DIN NH4 blade fuse from the TeSys GS range, rated 800 A at 500 V AC with an aM (motor-protection) curve. It is a single-piece fuse without striker, designed for motor branch-circuit protection where the aM characteristic allows high inrush without nuisance opening.
The aM curve means it is sized for motor starting — it will hold through the inrush of a large induction motor but clear quickly on a sustained overload or short circuit. The 500 V AC rating is the maximum system voltage it can interrupt; do not apply above that. The NH4 form factor is a standard DIN blade size — the fuse fits NH4 fuse holders and switch-disconnectors common in European-style distribution panels.