See this video.
Most of us who are not keeping our sibs on a trailer towed by the car need a way of getting the outfit to the water. If you set it up by the car and load with even just the outboard you won't be able to carry it. Even the sib alone may be too difficult to carry unless a very short distance.
So we will usually have either a launch trolley or transom wheels which can be removed or flipped into the up position once launched. Then you can set the sib up with OB, fuel tank and all your kit to trundle it to the water.
You may wish to think of what happens if you reach a destination where you want to pull the sib out of the water for a lunch or picnic etc. With transom wheels that are flipped up when travelling on the water you can put them down and pull the outfit from the water at a destination beach or slipway.
If at your coast location it gets busy and there is the possibility of having to park and setup some minutes walk from the water transom wheels are a life saver.
The Honwave air floor takes just one specific transom wheel type where you pull a pin out to move them from down to up. Here they are in the up position...