Hybrid slats have a copper top side that supports the part being cut. The balance of the slat being made of steel. Copper inserts are pressed into matching cavities in the steel portion of the slat. You get the benefit of 6 to 8 times improved life with copper on the top surface without the higher cost associated with a full copper slat.
Hybrid slats are ideal for applications where thinner material up to 7 gage (.179 thick) is being cut. Due to the two part construction they are not quite as strong as the solid copper slats.
Solid copper slats can be expensive when made for laser machines with wide slats. For wide slats you get the cost effectiveness of copper under the part and steel construction for most of the slat.