It comes with an extendable bar so that it can be centred on almost any wheelchair, (mine being large chair). It attaches to the chair with 2 quick release clamps left bolted to wheelchair frame.

The actuator is designed to be clamped to the handle, but on mine I feed the cable through the chair and clamp the speed unit to my armrest so I can use it myself. A key is needed to power the speed actuater.

A strong web fabric strap is provided to loop over handles to raise power pack wheels off ground for free wheeling use.

For grip the unit is quite heavy and has another strap to provide a downward force. I am easily able to twist my torso to loop the lift strap onto the handles.
We tested it by taking a walk around the local park a few times and it easily managed the terrain and its ups and downs. I have not tested off-road but as long as surface is hard and flat it should cope. I have charged the battery both on mains and car power. The motor runs forward and reverse, turning is a bit of a chore but practice helps.

I keep my chair in the car along with the power pack and I found if the chair is standing upright the the pack will fit in the space between the front and back wheels. In conclusion I am glad I got around to buying this power pack as it gives me more control over where I go and frees up my partner from pushing me.
Highly recommend.