The TCL-X100 is designed to extend the focal length from 23mm to 33mm, which is equivalent to 50mm in 35mm viewing angle terms.
Due out next month, at a price yet to be announced, the converter is built from four elements in four groups.
The cameras must first be updated to the latest firmware (version 2.10 or later on the X100 and version 1.20 or later on the X100S).
A wide-conversion lens is already available for the X100 and X100S.