Zhaga Interface Specification Book 4 defines the interfaces of high-intensity LED light engines (LLEs) comprising a rectangular, non-socketable LED module with a separate LED driver (electronic control gear).

There are three LLE categories in Book 4, which are defined by the size of the rectangular light-emitting surface (LES):

• 30 mm x 7.5 mm
• 42 mm x 10.5 mm
• 60 mm x 15.0 mm

Book 4 LLEs are intended for applications that need a high-intensity light source, such as street lighting and industrial high-bay applications.