I used Meguiar's Ultimate Protectant, Dash & Trim Restorer - but I would imagine any similar type of product would produce a similar result. Naturally, the potential extent of the improvement depends upon how dry and hard the rubber fittings were before being treated. All of the rubber and vinyl on my i20N was very dry even when I got it new about a year ago (the vinyl around the front seats is still becoming more supple and just now starting to feel nice and flexible after about half a dozen treatments over the last year, for example).