Balanced to 18,000 RPM. Tolerance is .0003" Maximum. Material is 42 CrMo - Hardness is HRC 50-52. Thread Tolerance Class is 4H-Class. Thread is M13 X .75.
Based on my observations, this collet chuck has a great balance and is sturdy enough for a wide range of workholding needs. The collets hold securely and the chuck itself is easy to attach and remove. However the price point may be a bit steep for occasional use..
Pros
Accurately holds various sizes of workpieces
Cons
Requires specialized collets for each different size
The outer box says ER16, the inner box says ER11 and that's right. Nice looking details, good finish, clean carvings, just not what I want. Send them back to her, get the right ones next time.