Worthless in grass yard, taller wheels and short axle make it prone to flipping sideways. Would be fine for paved or pea gravel trails, not slanted sideways on unlevel ground or soft grass yards. Seems top heavy with taller wheels. Would be really great if one could slide the axle out wider while outside and move it back when indoors so you could get through hallways. This dual feature would sell like hot cakes!! Also, what's with the "hard as a rock" knee rest? Boney knees %26 shins have to rest on there. Knee rest should have the consistency of a COLLEGE WRESTLING MAT. I wouldn't want to sit on this, let alone kneel on it. Maybe the "Hard Seat" is so you have to get knee surgery later on and then have to buy a walker? $$$