3sk41 Datasheet [new] -

Often found in a 4-pin TO-72 metal can or similar small plastic packages. Functional Roles

Modern silicon N-channel dual-gate MOSFETs (though they often come in SOT packages). 3sk41 datasheet

It is currently considered an obsolete or "hard-to-find" part but can still be sourced through specialty electronic distributors like Jotrin Electronics Often found in a 4-pin TO-72 metal can