This is a metal gear 3-wire Digital  Servo by parkzone with one arm.

Used with:(Not limited to)

• Typhoon 2 3D RTF Electric
• Typhoon 2 3D PNP
• T-28 Trojan PNP
• F4U Corsair RTF
• F4U Corsair PNP
• Messerschmitt Bf-109G PNP
• Messerschmitt Bf-109G BNF
• T-28D Trojan PNP
• T-28D Trojan BNF
• Extra 300 PNP
• Extra 300 BNF
• Habu EDF PNP
• Habu EDF BNF