The Zhaga Consortium has published Zhaga Interface Specification Book 2 defining a solid-state lighting (SSL) module primarily for downlight applications. Zhaga has also created a database of certified products, which are all commercially available.

Zhaga, an international group of lighting industry companies, develops interface specifications (Books) that enable the interchangeability of LED light engines made by different manufacturers.

Zhaga Interface Specification Book 2 describes a cylindrical, socketable LED light engine with integrated electronic control gear (ECG), commonly termed the driver. The light engine has maximum dimensions of 70.2 mm and 45 mm height. The diameter of the circular light-emitting surface is typically 59 mm. The light engine can be locked into a holder in the luminaire by means of a twisting motion. One use of this type of LED light engine is in downlighting applications.

"The publication of Book 2 provides full access to this specification for the entire lighting industry, not just Zhaga members, allowing companies to design their products to be interchangeable with other Zhaga-based products," said Menno Treffers, secretary-general of the Zhaga Consortium.

Products designed and certified according to Zhaga Interface Specification Book 2 – including LED luminaires, LED modules, holders, and LED light engines – are already commercially available from a range of different suppliers. The database of products will be constantly updated as new certified products reach the market.

In October 2012, Zhaga published Book 1 and Book 3, which respectively include common definitions and generic information applicable to all the different interface specifications, and interface definitions between a non-socketable LED light engine with separate ECG that has a round light-emitting surface measuring between 9 mm and 23 mm diam.

Several other specifications (Books 4, 5, 6, 7 and 8) have been approved by Zhaga, but at present these specifications are available to Zhaga members only. Other specifications are also in development.

Each interface specification, or Book, is developed by cooperation between the member companies of Zhaga. Once the certification procedure is in place for a particular Book, and once the first certified products have been sold, then Zhaga’s policy is to publish the full specification. Only products that have been through the full Zhaga test and certification procedure, which is performed by third-party laboratories, are entitled to use the Zhaga logo. Non-members are able to use the published specifications to design Zhaga-based products, but they cannot have their products certified unless they join Zhaga.