While all mats are black and lie flat on the ground, similarities between mats end there. The re-vulcanization process can produce excellent mats at a much lower cost than virgin rubber. It's important to find the right manufacturer.
Large mats tend to be extremely heavy and impossible to maneuver into a stall.
Trimming them is a nightmare. Pre-trimmed mats, unless they are of an interlocking design, are a fanciful creation. This type of precision cannot be achieved by a non-interlocking stall mat trimmed on the factory floor. This is the type of mat you should be looking for. This will ensure that urine will remain on the surface of such a floor long enough for the bedding to absorb it.