Mat is a random combination of fibers. For epoxy
you will need to use a stitched mat. For polyester you can use a mat that is bound together with a binder this is dissolved with resin hardener matrix. Cloth can come in many variations either woven or stitched. Mat is not as structural with out getting to technical mat is mostly used as the outside layer next to the gel coat to prevent printout of the laminate or as a filler. Cloth or stitched fibers have allot more strength. If you are new to working with all this stuff, I would advise that you practice on some other material first a piece of plywood
. If the repair is vertical you will especially need to practice as the resin will drain out of your chosen laminating material. There are a couple of tricks to prevent this.