I started using X-ACTO knives when I was taking design classes and needed to cut foam core to make models. A regular utility knife didn't have the same precision as the X-ACTO and the refill blades were a lot cheaper. The barrels of the knife is almost the same as a pen or pencil except there is a textured pattern on it so you can get a solid grip on it when using it. One of the best things about the X-ACTO is that the tips are extremely sharp so if you need to cut something out of the middle of poster board, foam core or cardboard you can puncture it with the tip then start to make the cut. Changing the blade is simple; just twist the locking neck collar open, remove the blade, insert a new one and screw the neck closed. There are special containers that you can get to dispose of the spent / used blades but I usually put a piece of tape over the blade and put it in a soda can with my recyclables. The amount of use you are going to get from each X-ACTO blade depends on what you are cutting. For thin paper you will be able to get more use from a blade than you would if you are using it to cut through cardboard or foam core. When I get a new X-ACTO knife I always take a permanent marker and make a design on the clear cap. That lets me see instantly if the cap is in place and it has helped me avoid accidents when I went to reach for one or toss it back in the drawer. These are sold in most arts and craft stores; the refills can be purchased in ten, twenty and fifty count packs as well as larger sized packs if you have a business that goes through them quickly.