The ET5 is a mutated TWIG frame that can accommodate 5" props. The frame is premium 3.5mm thick high grade T700 carbon cut along the weave and chamfered on both sides interior and exterior edges at .8mm. The frame measures approximately 200mm from motor post to motor post. Motor mounting is for 4-hole 9x9 or 12x12 motor mounts. You do not have to use t-mount motors as there are also a lot of 5mm shaft motors from 15xx to 16xx that are great choices as well as lots of 5mm 5" shaft props to choose from on the market. We highly recommend keeping your motors under 18 grams since this is a lightweight frame.