It's two leashes and they get entwined together, and believe me, they're needed
She's on her 4th harness, as I forgot to take the first three off when she was in the back of my SUV and she managed to slip out of them and chew them to bits
There's two rings on this one (it's a KONG, and they make great hard wearing stuff) so it's a pretty rugged harness and so far, it's stayed on
She's incredibly strong for a medium sized dog
A mate of mine did a sled dog trip in Scandinavia and said the dogs were about her size, and easily pulled a 350 lb sled plus him and he's 200 lbs, 4 dogs in each team
He said you don't want to fall off, as they just keep going ;-)