The Crescent 3" Offset Handle Hand Seamer, part WS4N. It has an offset head that keeps the hand clear of the work. Supplier specification: OFFSET HAND SEAMER 3".
A hand seamer bends and flattens sheet-metal edges to a set width, which is how a lock seam is closed without a brake. Straight jaws work along an open edge; an offset seamer keeps the hand clear when the work has already been turned up.
