These are hard plastic as others have said, but I've used a lot of these pens and these have lasted the longest. They're also the hardest to find. There are ones by Manuscript that have a hole so you can see how much ink is left. These are the worst to purchase. They're also hard, but smooth plastic. They break incredibly easy. If you drop them on a hard floor, they immediately crack. I've had three of these and they're $22.00 each. Instead I buy the pens shown here and they last forever. I didn't think I'd like the colored ink, but I've learn to enjoy them. I would definitely recommend these pens!
I purchased this product and within seven (7) days of receipt, two of the four (4) pens developed cracks in them where the body of the pen joins the Nib mechanism!