The bibs are 100% cotton and fully reversible. The cotton is thick, good quality Jersey, so it is nice and absorbent for the super-dribbly times (when you're drying the bibs on the radiators after only 30mins wear). I liked the fact that there is a choice of plain and patterned bibs - to allow maximum flexibility with outfits.
The bibs fasten with a single, plastic popper, which means that they can hang quite low around the neck, but I think that this allows for good manoeuvrability of the 'chomper'. The key part of the bib is a rubbery, soft, plastic chomper. It is textured and really easy for little hands to hold and chew on - it is particularly good for those first front 8 teeth.
I would highly recommend buying one, they are a little expensive at about £9-£12 for one, however I bought one (the cheapest price was eBay) and hand washed it in hot water each night so that it was ready for the days when N really needed it.
I bought the cheeky chomper bib myself, I have written this review as a genuine recommendation and I wasn't approached to write it by any company.