#63190 - No blade changing required - just break off used blade and get a new sharp blade. Each master blade has 8 snap-off blades. Two extra master blades are included for a total of 24 blades.
#63191 - Our most popular utility knife. Long-lasting, heavy-duty with a durable metal casing. Retractable blade has 3 locking positions. Includes 4 blades.