Marvel Thor Strength of Asgard Girls Tanks The Marvel Thor Strength of Asgard Heather Black Racerback Tank Top pays tribute to a superhero worthy of a spot in the Avengers: Thor! A distressed print on the front of this soft black Thor shirt reads "The Strength of Asgard Thor" around Mjolnir, Thor's incredible hammer. 50% Polyester, 25% Cotton, 25% Rayon. Designed with raw-edge hems. Designed with raw-edge hems.