Chews.

[Karran]

Fluffy rabbit/lamb/cow ears.
Braided lamb (JR Pet products)
Anything ostrichy
A new pet shop opened near me so I've literally just come back with a dried lamb leg each, so far it's been 20 minutes of contented gnawing and they've not made a dent!

 

[Moobli]

Tup horns are good for being long lasting, but ewe horns are better as they are more pliable and easy to chew. Mine love them.