I have a set of Performance - Technique and it looks like the rollers are 4.25. It has a fan with adjustable resistance. The rollers were given to me by a friend. I'm ok on them clipped in and running through the gears but no standing. In your home you will need to train on a doorway or near something you can grab. I have noticed no one in this thread talks about grabbing a remote and changing the channel! That is more of a challenge then riding with no hands! if you have about $900 I would buy the e- motion rollers, those rock. Check out the you tube vids on e motion rollers and even the home made freemotion rollers. There is a version on this forum too. I have made a version for my rollers and they are a lot more friendly allowing me to stand up and sprint.