Prefix Main Cap Puller works on Gen 3, 4 & 5 VIPER blocks as well as Gen 3 Hemi main caps 5.7L/6.1L/6.2L/6.4L cast iron blocks, as well as the 6.1L and 6.4L aluminum Mopar blocks. All machined aluminum construction and black anodized. No more using screw drivers to get the caps off!