STANLEY The Easy Fill Flask in Black. STANLEY The Easy Fill Flask in Black. It's the flask that never lets you down - unless of course, it's empty. The retro look, portable size, and slim silhouette means that it can slip seamlessly into any situation. There's a wide mouth opening for easy refills (no funnel needed). And the stainless steel construction with leakproof cap makes it extra durable.. 18/8 stainless steel, BPA-free. Leakproof + packable. Never-lose cap with wide mouth opening. Holds approx 8 oz. SNLE-WH68. 10-00837-346.