DrawWorks understands the importance of casing integrity. This is why we have begun developing a non-marking insert to use on the DWCRT family.
The current inserts penetrate less than 5% of the wall thickness. This maybe too much damage for some, so we are working to develop a proprietary gripping method to eliminate damage to the ID of the casing. Contact DrawWorks for any questions or to find that status of our latest testing results.