Great alternatives to scissors, especially when travelling.

They also make very useful keyrings.
Measurements: 

Available as:

* a thread cutter, with fine "teeth" to catch the thread when cutting - in an antique gold finish. The diameter of the disc is 3cm.
* a yarn cutter, with slightly wider gaps to catch the yarn when cutting - in an antique silver or gold finish. The diameter of the yarn cutter disc is slightly bigger, at 3.5cm.