Often used in high-vibration applications that could cause standard thread sealants to fail, these never fully harden and remain pliable enough to self-heal and stop leaks before they start. Formulated without PTFE, these sealants are less slippery and less likely to result in overtightenting than sealants that have PTFE, making them good for plastic pipe where overtightening could lead to cracks and breaks. They have low locking strength, so they can be adjusted without tools.