Slabbing is the same as with coins. Chips are put into sealed plastic "slabs" with a grading given the same as coins. The consensus is that there is no need to grade the chips that accurately and no one wants to pay the extra $10-$20 for the slabbing fee. It was started about 10 years ago but due to club resistance mostly died very quickly. Strangely a few years ago a place 45 minutes from here started trying to slab them again but I have not seen them for the last year or two.