These mechanical pencils are a decent deal for the price. The only annoying thing is the rubber grip does not stay in place. It moves and slides around. The grips aren't all that comfortable anyway so I just take them off.
These mechanical pencils are extremely inexpensive but they are not the highest quality. I don't believe you can replace the eraser and the plastic clip breaks easily. If you want a pencil that you won't care about breaking or losing this is a good option.