Astro Pneumatic 4577 Mobile Step Masking Machine The Astro Pneumatic 4577 Mobile Step Masking Machine is lightweight, easy to use and portable, and can dispense rolls up to 18” wide. A sharp, anodized blade allows for smooth cutting. With a load capacity of 220lbs, the Astro Pneumatic 4577 Mobile Step Masking Machine can also be used as a step stool.