Heat Backpacks & Travels BlackPorter Yoshida & Co "Heat" sports backpack constructed of 66 strand woven varistor nylon in the main areas, combined with waterproof industrial tarp inserts. The silhouette features a solid structure thanks to high density nylon tape reinforcements, which maintain the shape and ensure practicality in daily use. The design incorporates functional elements such as ribbons sewn at regular intervals and attachment systems inspired by military details.