I hang my two lines, each 2 meters long (Trixie Modern Art Leash Time Flies 2.00 m 20 mm) left and right on the chest and shoulder and used the shock absorber between leash and collar. If the dog times make a jerky movement or pull to the side (to sniff) then the shock absorber is simply ideal! In addition, my zusäzlichen 33 cm length are quite right, because the dogs have a little more freedom.
I am very satisfied and if a shock absorber decreases, or will be eventually broken, I will buy more.