Size M Only used once. Washed. Shrunk one size due to washing, so it's equivalent to size S. [See photo 2 for reference] The BESTBER grip T-shirt has a high-grip print on the back for a non-slip effect. The non-slip feature makes it easier to form a bridge during bench presses and prevents the back from moving and collapsing the bridge during the exercise. The stability of the bridge not only stabilizes the form and improves performance but also helps prevent injuries. Machine training, non-slip effect Squats & Machine Training The non-slip effect allows for stable form training even with hack squats, leg presses, and barbell squats. Stabilizing the core allows you to use the power of your entire body more efficiently for lifting, enabling you to handle heavier weights. As a result, it also leads to an increase in muscle strength and mass.