Recycling by product massive number of types of plastic, they each carry a resin identification code, and must be sorted before they can be recycled. This can be costly; while metals can be sorted using electromagnets, no such 'easy sorting' capability exists for plastics. In addition to this, while labels do not need to be removed from bottles for recycling, lids are often made from a different kind of non-recyclable plastic. To help in identifying the materials in various plastic items, resin identification code numbers 1-6 have been assigned to six common kinds of recyclable plastic resins, with the number 7 indicating any
Recycling symbol may use or modify the recycling symbol, royalty-free. Though use of the symbol is regulated by law in some countries, countless variants of it exist worldwide. Anderson's original proposal had the arrows form a triangle standing on its tip—upside down compared with the versions most commonly seen today—but the CCA, in adopting Anderson's design, rotated it 60° to stand on its base instead. Both Anderson's proposal and CCA's designs form a Möbius strip with "one" half-twist by having two of the arrows fold over each other, and one fold under, thereby canceling out one of the other folds. However, most