SAFERSTACK frame stacks in 30% less space than regular frames, allowing the user to be more efficient when moving to and from the job site * Frames interlock for safer storage and transport, helping to prevent stacked frames from sliding * Scaffold frames have a durable, long lasting blue anti-slip textured powder-coat finish for superior grip and secure footing when climbing * Perimeter tubes 1-5/8in. O.D.(13 ga. steel), interior tubes 1in.(16 ga. steel) * Pin spacing is 4ft., the industry standard that"s compatible with most scaffolding