The rest is pure fun. For both sides, because this toy is suitable for throwing and retrieving as well as Zerr- and chew. As a challenge to also be more balls, more chewing bones etc. Press in the ball
For durability: After about 6 months daily wager at a now good 2 year old GR while there has one or the other Blessur suffered, but I'm quite confident that it will still hold at least 1 or 2 years.
Not should also be mentioned that I did not came up when unpacking the unconditional desire to return there immediately again: not a shred of evil chemical stench that Fellnase has sniffed briefly about and wanted since immediately so that play (and mine is as pretty reticent when chemistry is not right).
Conclusion: Not for smaller dogs, but should it ever need to be sorted is bought immediately a new one.