The Angus A-5 has more rigid foam, more rigid dividers, more reflective tape for your safety, better more fluid resistance removable bottom, more 1000D CORDURA® fabric to make the bag, better shoulder strap. Just plain better.
The BT-21 will hold a "D" tank. There's also a pocket on the main body that's large enough to hold a BVM, handheld suction unit and oxygen accessories. Oral airways and nasal cannulas can be stored in the small pocket on the regulator protector cover. The hinge on the protective cover means it will never get lost. The BT-21 is made of durable 1000D CORDURA® fabric. The "D" tank bag is available in red, green and navy blue options.