Crack inducers are designed to induce controlled cracking in concrete. Surface crack inducers are a steel profile that is pressed into wet concrete to induce a crack. They are often capped with a permanent cap to create an aesthetically pleasing joint.
Ground crack inducers are designed to induce a crack from the bottom of the slab upwards. The triangular plastic profile is placed prior to pouring. Once the concrete has been finished, a joint is cut above the location of the ground crack inducer cause the concrete to crack along the joint.