MYLAPS RC4 Pro Transponder (lighter, smaller, all black) RC4PROIts lighter. Its smaller. Its all black. Introducing the RC4 Pro, the worlds smallest transponder that helps you race in style. The RC4 Pro Transponder takes the Racer to the next level. Pitch black design The RC4 Pro Transponder features a shorter 8 cm 3. 15 in cable, ensuring a perfect fit every time. And the pitch black design gives any RC car that beautiful finish it deserves. The transponder comes in at only 3 grams, making it almost as light as