Hyde Tools 42047 18mm Snap-Off Blade Utility Knife

Short extension for pressure work and box scoring; long extension only for the full-depth foam pass, and only with the positive lock engaged. The lock is a two-motion deliberate act — position, then lock — so use it; an unlocked blade run out at depth is the classic way to snap a segment mid-cut. Snap at the drag, not at the visible dullness. By the time a wide blade looks dull it has been dragging for several cuts; renew at the first change in how the cut parts. Snap safely. Cover the blade break line — the snapper cap, pliers with a rag, or the dispenser's snap feature — and snap away from your body; an 18mm segment is a stiff, sharp shard and it can flick. Keep the used segments contained — snapped blades are the sharpest waste a jobsite makes; the 9mm 42356 dispenser (sibling line member) is the family's built-in sharps answer, and even the 18mm operator should have a dedicated sharps container, never a loose trash bag. Carbon steel wants to stay dry — wipe the blade after wet or adhesive work; a fresh segment is always seconds away, but the installed one will bloom rust if left wet.