Surely a DOG LEAD is a dog lead? Any old lead will do? It does what it's supposed to do? No, not really, in my experience there are good DOG LEADS and bad leads and I've used plenty of both over the years. Ones that have stopped the circulation to my hand as I have wrapped it around, ones that have burnt my hand when the extendable bit extended far too quickly and ones that have only lasted a matter of days.
One dog lead that I am using at the moment which I am particularly impressed with is the Long Paws Comfort Leash. It's not extendable, it's not a bungee, but it's a STRONG DOG LEAD & a SECURE DOG LEAD. The main reason why I like it is because it has a soft neoprene handle which makes it very comfortable on my poor old hands or up my arm if I need both HANDS FREE. As I said it's not a BUNGEE DOG LEAD but the rope has a small amount of spring which will absorb the initial pull shock but still maintaining overall control.
The clip is a CARABINER with a SAFETY LOCK to prevent that ever hopeful runaway with a swivel action to avoid the rope twisting around and around. It is actually quite a simple design but as I very often say, it's the simple things in life that pleases us, isn't it!