yacoub,
That is Kydex. It is actually an excellent material. If you search around at various dealers and makers you will find most sheatsh are made of Kydex these days, at least for combat and edc type of knives. Leather is great but, it has been known to rot(being the skin of a dead animal) even thoug treated it can corrode although over a very long amount of time.
Kydex however, doesn't corrode at all. The only fault possible that I know of or have experienced is wearing down over time, which I have also experienced with Leather sheaths. Pulling the knife out often and back in often can, wear down the molded areas around the blade, even with leather.
I have cut straight through leather a couple times in my life by re sheathing a knife in a hurry.
I have never done that with Kydex. Trust your Kydex, use it without fear of hurting the blade or the sheath. It will serve you well.
The only regular damage for fixed blades and kydex that is without question are the Kydex scuffs.
Kydex because it's harder than leather will scuff the finish of your blade. Just a fact of life and especially with "user" grade blades, a non issue for the average knife carrying/using joe.
Thank you however, for your kind words! Glad you like the Model 10!
Regards,
Rich