Tippet rings or rig rings as I think they call them in the carp world .....
I really like them as, in the result of a tangle or too short a snood, you can simply retie a length on and be back fishing very quickly.
I cannot recall the last time I fished one fly only. Perhaps to my detriment. Two flies, yes, Three flies, generally and four if I am feeling brave
Having been lucky enough to land a fair number of double up trout, it is not too difficult to manage but three was a slightly different story
Ben