Complex sentence: It is the sister promotion to the Ultimate Fighting Championship (UFC), both owned and produced by Zuffa, with a focus on the lighter weight classes (155,145, and 135 lb).
Split into simpler sentences: It is the sister promotion to the Ultimate Fighting Championship (UFC), both owned and produced by Zuffa. The WEC is made up of 3 weight classes, (155,145, and 135 lb).