There are few important factors are taken into account in making perfect leash. 
Leather selection – you can only use specific cow hides to make sure that leather does not stretch too much. Leather should be flexible in balanced way.

General "Woof" leash  Tip: We only use best leather and nylon when make our dog leashes

We do not like making leashes to soft like rope or too hard like plastic.We use vegetable or chrome tanned leather which is perfect for making leash which is pleasure to use daily.

General "Woof" leash  Tip: To make this lead high quality product we used selected leather hides

 Second factor is snap – there are several types of snaps and there are many materials which are used for making snaps for leashes. We believe in using brass plated snap hooks which are reliable over long period of time and very strong in regards to tension and pressure.Of course the best is stainless steel and we use those as well, however please note that stainless steel snaps are expansive.When you make your decision about purchasing leash please think about for how long you would like to use it.

General "Woof" leash  Tip: If you feel that after reading this info you still have questions about ordering correct type leash please call, email or fax us and we will answer your additional questions and will help with selecting right leash for your dog and task

So you might realize that usually paying $10-30 extra for better leash which can be used for 6-10 years is wise decision.Third factor is how leash is assembled.
 Handle and snap can be riveted, hand stitched, machine stitched, braided or combination of mentioned ways.I think less stress points there are stronger this leash will be. I prefer braiding without additional rivet. However any other way when properly done .Can be strong enough. And of course depending on the dogs size and your task – walking, tracking, training, agitation, tie out etc. you should consider design.You are welcome to contact us so we can help you to choose most appropriate leash for your goal.