I've used this for years and love it. It makes cooking a pot roast easy and I just use a big glass dish. But the recipe on the package is for a big 3-4 lb roast, so be sure to use the times listed at the bottom for the smaller 2 1/2 pound roasts we usually find in our stores here. I use a probe thermometer to check temps at about 1 1/4 hour. Just poke it right through the bag's tiny holes you've created.