To celebrate being in business 20 years, a group of stores in Europe has been given a limited edition size of Mutant’s well known mass gainer Mutant Mass. The product is in fact a bonus version of its larger bag size, which usually weighs in at 6.8kgs. For a very limited time in Sweden, Finland and Denmark you can get a 20% extra bag weighing in at 8.1kgs. Mutant Mass fans interested in grabbing the bonus supplement while it’s available can head to BodyStore for Denmark, Fitness Tukku for Finland, and Gym Grossisten for Sweden.