[Emmurz]

Robos are speedy little things so like others have said they'll most likely slip out in any wheel.
Silent spinners are brilliant wheels, My little syrian Chomp currently has a regular and will be upgrading to a larger Rolly wheel sometime soon when he outgrows his current one.
I'd say go for a SS for your robos, they look good and are great for your little ones plus they don't break the bank and you can pick them up at plenty of different pet stores.