What's the difference between single-layer and double-layer ABS sheets?

Structural differences: 

Single-layer ABS sheets are made from a single layer of ABS material, with a simple structure. Double-layer ABS sheets consist of two layers of ABS, which may be one layer of virgin material and one layer of recycled material, or even one material in two colors.

Process differences: 

Single-layer ABS sheets are typically produced using one extruder, while double-layer ABS sheets are produced using two extruders.

Application differences:

 Single-layer ABS sheets are usually used in less demanding applications, such as ordinary offices and small conference rooms. Double-layer ABS sheets are mainly used in large conference rooms and can also be used for thermoforming refrigerator