This is the TQi Telemetry Expander from Traxxas.
FEATURES: Support six plug and play "smart" sensors (not included) as well as
the three standard sensors
Accepts the GPS Speed Module (not included, order TRAM6551) that
provides accurate speed on both nitro and electric models
INCLUDES: TQi Telemetry Expander with Receiver Cable
REQUIRES: Traxxas TQi radio system with the #6511 Traxxas Link Wireless Module
#6518 Traxxas Link Receiver
Apple iPhone (4S, 5, 5C, 5S), iPod touch (5th generation & later)
iPad (3rd generation & later)
iPad mini, or Android 4.4 equipped device
Traxxas Link App (available free on Google Play and the App Store)
Mounting Kit Depending on Vehicle;
#6554, Rustler, Bandit, Slash 2WD
#6555, Slash 4X4, Stampede 4X4, Rally, Jato
#6556, XO-1, E-Revo*, Summit*, all Maxx trucks, Revo 3.3, Slayer
#6558, Funny Car, Nitro 4-Tec
*Requires #5632 Chassis Brace, TRAC5633
BOX DIMENSIONS: 3.75" W. X 1.75" H. X 4.25" L.
BOX WEIGHT: .18 LBS.