All Enhanced Definition Lens Tubes (EDLT) are recommended for use in both regular incandescent Source Fours and Source Four LED fixtures, as well as ColorSource LED fixtures
However, there is one exception - the 50 degree LED EDLT. It is only approved for use with our LED fixtures. If used in a regular Source Four fixture it will burn through gel quicker, due to the hot spot that is created, and you'll be unable to create a hard edge. The 50 degree LED EDLT uses a larger 7.5" gel frame, while the standard 50 degree EDLT lens uses the 6.25" gel frame.
For more information, see this article: Difference between 50 degree lens for LED and standard fixtures 450EDLT