There are lots of threads on this already, just do a forum search of "wood safe"---and I've got details in both of my NobEssence reviews up (Romp and P Spot Flogger).
Basically, they've got a completely waterproof coating. So because no water/oxygen can ever get in, the wood will neither rot, nor expand/contract (which is what would cause splinters). So they really are good forever, with no splinters.
Just don't chip the coating (I've found mine to be pretty durable) or you'll have to retire it to sculpture-only status.