Abstract: A coupling device for interconnecting first and second slender members includes a positioning sleeve sleeved on one end of the first slender member and having a radial outward stop flange and a radial stop projection at opposite ends thereof. An externally threaded sleeve is sleeved and secured on one end of the second slender member, and has an externally threaded front-end portion. A nut member is sleeved on the positioning sleeve, and has a surrounding wall for engaging the externally threaded sleeve. A limiting member is sleeved between the nut member and the stop projection of the positioning sleeve, thereby arresting movement of the nut member from a fully tightened position.