Carlsson Swedish Upright Bass Rosin is a premium rosin which comes in an easy to use foil cup. Many players carry more than one kind of rosin due to humidity and dry climates. When the humidity is high, the harder rosin is usually best. The Carlsson Swedish Upright Bass Rosin is a premium hard rosin, and is known as often being the top choice for orchestral players everywhere. It’s packaged in an easy to use airtight plastic flip-top storage cup with a relatively neutral consistency.