These are hands down the best way to weave in ends when crocheting.  Simply slide the hook down the row you will be weaving the ends into and thread the yarn to pull through.  I find using these hooks with a hole much easier than using a blunt eye needle.  The 10mm hook even fits the 5mm bobbiny cord and up to the maxi 9-11mm bobilon T-shit yarn.  They are made from bleached bamboo and are so very lovey.  
 
The set comes with the following 9 sizes;
4mm
4.5mm
5mm
5.5mm
6mm
6.5mm
8mm
9mm
10mm