1st Generation: Disposable type, disposed after the lead had finished. (When the pencil tip move up/down during writing, means that the lead had finished)

2nd Generation: Refillable, replace the lead from the refill tube and continue writing. (When the pencil tip move up/down during writing, means that the lead had finished. Pull out the eraser cap, insert one refill lead into the pencil, cover back the eraser cap and continue to write)