Hot Racing Differential Locker Spool: Traxxas Made by Hot Racing; Hot Racing is a United States based company; parts are sourced from Chinese producers All Hot Racing upgrade parts are direct replacements for stock components; additional parts are not required Hot Racing part number SRVO1025; UPC 083745451931 This item works with: Traxxas E-Maxx, E-Maxx 3903 Brushed, E-Maxx 3908 Brushless, E-Revo 5603 5605 5608, Revo 3.3 5309, T-Maxx 3.3 4909