Recycling codes are used to identify the materials out of which the item is made, to facilitate easier recycling process. The presence on an item of a recycling code, a chasing arrows logo, or a resin code, is not an automatic indicator that a material is recyclable; it is an explanation of what the item is made of. Codes have been developed for batteries, biomatter/organic material, glass, metals, paper, and plastics.[citation needed] Various countries have adopted different codes. For example, the table below shows the polymer resin (plastic) codes. In the United States there are fewer, because ABS is placed with "others" in group 7.
A number of countries have a finer-grained system with more recycling codes. For example, China's polymer identification system has seven different classifications of plastic, five different symbols for post-consumer paths, and 140 identification codes.[1] The lack of a code system in some countries has encouraged those who fabricate their own plastic products, such as RepRap and other prosumer 3-D printer users, to adopt a voluntary recycling code based on the more comprehensive Chinese system.[2]