Finally, the restock you've been waiting for! OTR Hard 2 Buff is an incredible, ultra permanent alcohol-based ink guaranteed to beat the buff. H2B is highly pigmented, opaque, and UV-resistant as well as Xylene free. A cult favorite since 1998! Refill size is 120ml/4oz. Hard to Buff Ink is suitable for indoor & outdoor use on paper, metal, plastic, glass, canvas, and more. Pair this powerful refill with your favorite empty On The Run Markers, Art Primo Mops, pump markers etc.