Who has not had to regret breaking the damn tongue male RJ45 plug? A force to plug and unplug it the locking tab inevitably ends up yielding. Should we then systematically change the 20 or 30 meters of cable that connect the box, located in a room to the computer that is on a different floor? The solution is to place a small cable 50 cm after the general. It is here that the coupler is playing its role. So when the damn tongue will break only the small cable will change in 30 seconds (provided you have planned a spare cable).