These joint protectors by Soff Cut are here to help eliminate incorrect breakage in concrete projects. Breaking generally occurs where two cut lines are crossed - at the joints. If joint cutting isn't done at the proper time, the new (or "green") concrete is too fragile and doesn't have the tensile strength for the cross cut to be done without breaking and crumbling. These joint protectors apply the right amount of pressure inside of the crack keeping the concrete in place while cutting is taking place which keeps it from cracking. They are packaged 150 per bag and are a tremendous time, money, and energy saver, a must have for all concrete applications.