Disclaimer that I haven't gone through them enough to claim durability. I trust Bosch as an established brand that puts the least effort into keeping their customers happy. I'm also on the looser side of the scale so I won't be running those 6 hours a day and I doubt I'll have any problems with that. They fit snugly in every brand of T25 bolts I've bought from [hardware store]; they should not wear out too quickly. They *should* last for years. A NOTICE. If you want to use the magnetic snap-in screw holders that fit these narrow shank bits, be aware that they are too short. In particular, we talk about the Dewalt magnetic case that comes with this kit: https://smile.amazon.com/gp/product/B00IOXB450. Dewalt bits are longer. I don't know if other brands of magnetic ring clasps will work with Bosch. If I find out I will update.