This is the 5A Voltage Regulator from FlightTech.

FEATURES: Provides voltage stability to meet the demands of today's high- performance radio systems.
Improves control during complex maneuvers requiring multiple servo  inputs at the same time.
Failsafe Switch . Built in overheat protection

INCLUDES: One 5A Voltage Regulator

Input Voltage: 6V-8.4V (Max 10V)
Output Voltage: 5V-6V (Adjustable)
Output Current: 0-5A (up to 30Watts)
Dimensions: 55 x 30 x 7mm (2.17" x 1.18" x 0.28")
Weight: 0.88 (25g)