Book 12 defines a family of rectangular and square LED arrays with a circular light-emitting surface (LES). These arrays require a separate LED driver, and can be used either with or without holders, depending on the luminaire type and application.

Book 12 Edition 1.1 also describes array holders.

The LED arrays in Book 12 have the following overall dimensions:

The holders in Book 12 have a cavity in the rear that accommodates a COB array. The size of the cavity corresponds to one of the array sizes shown in the Table above.

The outer dimensions of the holder correspond to the LED modules defined in Zhaga Book 10 i.e an outer diameter of either 35 mm (category D35) or 50 mm (category D50).

The combination of a COB module and a suitably sized COB holder can create a product that effectively replicates a Zhaga-based spot LED module as described in Book 10.