Permatex High Strength Threadlocker 6ml Red High-Strength Threadlocker. Permatex®. Red. OEM specified as 271™. High-strength threadlocker for heavy-duty applications. well-suited for permanently locking studs and bolts. Locks against vibration loosening. Requires extra effort or special tools for removal. For fasteners sized 3/8" to 1" (9.5-25mm). Temperature range: -65° F. to 300° F.