This is the E-Flite 9.0 Gram Sub-Micro G90 Heading Lock Gyro.  This multi-feature gyro boasts two modes (Heading Lock and Standard Rate) and compatibility with digital or standard servos, among many other features - all of this and it's lightweight too.

Key Features

• Heading Lock or Standard Rate modes
• User-selectable modes that optimize performance for digital or standard servos
• On-gyro single gain setting adjustment capability
• Optional dual remote gain setting and mode adjustment capability
• Built-in drift cancellation and temperature compensation circuitry
• Extremely lightweight - only 9.0 g (.32 oz), including leads and connectors
• Sub-micro size - just 20 x 20 x 15mm (0.8 x 0.8 x 0.6 in)

 Specifications:

Type: Sub-Micro
Sensor Type: Piezoelectric Ceramic
Weight: .32 oz (9.0g)
Dimensions (WxLxH): 0.8 x 0.8 x 0.6 in (20 x 20 x 15mm)
Gain Type: Single on-gyro or dual remote
Operating Voltage: 4.2 - 8.0V
Reversing Switch: Yes
High/Low Frame Rate Select: Yes - Standard/Analog Servo and Digital Servo Support