Octura 1/4-28 Threaded motor coupler for .187 (3/16") flex cable drive system. Used with Nitro Fuel Motors.Note: This coupler is for a NITRO Engine! Will not work with an electric motor!Fits motors 1/4-28 threaded shaft. Fits, flex cable with a diameter of .187 (3/16", 4.75mm)Length: 1.3" (33mm)