This is a Helvar L15A 15w wire wound choke to run 1 x 15w T8 Fluorescent Tube

this item is obsolete we are offering the L20A-He please see link 

https://www.easy-controlgear.com/products/helvar-l20a-p240e-he-18-36w-magnetic-cfl-ballast?_pos=1&_sid=5320d733e&_ss=r