Ruby is a professional chewer! Nylabones do well for her, but make sure that you get the ones designated for power chewers (or else he'll tear it into little chunks). They're usually color coded with a red slash on the package. These last a while for my beagles - months even. I have a bunch of medium sized ones just laying on the floor throughout the house. They'll just casually pick one up and chew on it for 15 minutes or more when they have the urge to chew. I just bought a giant one for Ruby, and she loves it! Poor bailey is a little smaller, and can't get a good grip on it.
I have a half dozen kongs, too. She's turned pro at emptying those suckers, too. But they last. I've only had to throw one away after almost a year. I experimented with so many other tough rubber toys, and Ru has destroyed most of them in days or even hours. I would however recommend these as well:
Starmark Everlasting Fun Ball - Get the larger one. It'll drive him crazy trying to get to the treats inside. Ru can easily get the treats out of the smaller one, since she can get her mouth around it, but it's lasted months and months. I give the smaller one now to Bailey, who isn't as destructive. Ru will just lay on the floor and lick the treats in the larger one, until they just fall out from shriveling. Of course, she leaves an unsightly puddle of saliva, so I limit how much she gets this one. I wish they made another intermediate size between the two that they offer.
Petstages Orka Jack - The big one without the rope (Ru eventually damaged the small one after a few months). You can put treats in it, and it keeps them busy, and it's hard for Ru to even get a good enough grip to cause major damage. I may get a second one, because it's the only toy that both dogs will fight over!
You can get all of these at PetSmart. Just do a search on the website to see what they look like.
Hope this helps! I've had a good tester.