These optical cables have a transport protection against dust and damage to the plug tip. It looks like a soft plastic dropper. Attention! This protection is necessary to pull off before you put the plug into a socket on the device. The glasses you should wear that you can see in which position you have to insert the plug. The part is not round! The sockets have a dust cover that if you put into the plug in the right position, opens inwards. This description is, unfortunately, not with most cables still in a minority of device descriptions. So: do not poke with force Soder see how it fits.