When I received the pen, and after first using the brush as instructed, I uncapped the other end. As described by many, I saw what I thought was the cleaning tip, a foam or sponge ball-like pad that seemed glued to a flat holder. First time I touched it to the lens, however, the ball fell off. Many have described this.
But here's the thing: As is clear in the pictures, the foam ball is ~not~ the cleaning tip, and it's not supposed to be glued to the flat rubber 'holder'. Instead, the flat rubber holder is the cleaning tip. The foam pad is the replenisher, meant to refresh the cleaning tip every time the pen is recapped. The only problem is that sometimes the foam pad can come out of the cap. But just push it back in and close the cap on the pen tightly. I did this and the ball has never fallen out again. This is a decent product. Enjoy it.
The rubber tip works nicely to remove smudges and grease from the lens. Just remember to use the brush first to remove dust.