These are great pens and the best part is that they are super-easy to change the cartridge with little to no mess (especially after the first time you do it). The only reason I did not give it a 5 rating is b/c the chisel tip pens tend to squeak when writing on the whiteboard. This is not the case for the bullet tip pens. I also find that the nib is much more durable than other similar-type pens (and I've used a lot of whiteboard markers in 25+ years of teaching). I'm anxious to try out the fine tip bullet pens. I would like to see these pens and refills more widely available b/c the styles and colours can be Out of Stock when I go to order them.