I would like to sound a note of caution about the Hartz Collar and Lead Combo, which I see is know stocked in quite a few supermarkets and grocery stores. I use this product myself for a single purpose. Every time I pop out to the mail box or laundry room my dog wants to come with me. He walks at heel but there is a leash requirement within the apartment building, so I keep this by the door. I can put it on and take it off one handed easy than a leash with a latch.
That said, I would never use this as a leash for going on a walk more than the twenty meters or so to my mailbox and back. I would not use it outside and never with a dog that would pull. In the package you could mistake this for being a budget-priced collar and leash. But actually it is a single nylon rope with a hand loop on one end and a noose style arrangement with a metal sliding ring on the other (see picture). This style of slip or kennel leash is rarely sold in retail stores because it isn't a great idea to use them other than for short, indoor transfers of animals.
A small leather tab is provided but the illustration on the package suggests this is intended to stop the noose end from opening far enough for the dog to slip out, not (as I had assumed) to stop it from closing too tight and choking the dog. It is not very effective for either function.
In my opinion the Hartz All in 1 Collar & Lead Combo should not be used in place of a normal collar and leash for dog walking due to it presenting a potential choking hazard for the dog. This lead should certainly never be used as a tether. It seems to me that the fine print disclaimer on the packaging is in no way sufficient when it comes to make the limitations of this product clear.