Passenger handles, a belt that fits over the rider's clothing to provide handles for the passenger.
A soft belt that sits on the rider's waist with a handle on each hip.
Regular for waist sizes up to 36 inches: Large for the others.
Warning this is not a safety device!
I purchased a Large and it fits snugly around my waist without slipping on my textile/weatherproof jacket. Previous rides with my partner had her slightly nervous when trying to find a comfortable place to hold on to me for long periods especially in the twisties. Now she feels a lot more confident on the back and is bugging me to go out on rides. (Thanks Andy!)