Mip no.1.5 pucks are a direct update for those users that find no.1 pucks screws are coming in contact with the aluminum outdrives over time. By switching over to the taller no.1.5 pucks it will effectively eliminate the chance of the capturing screw head coming in contact with the Outdrive face during wear or articulation, since the screw head is now up and out of the way. And being that the no.1.5 pucks is taller there's now more surface area for the system to spread load, which will improve overall wear. No.1 pucks and pins will always be usable in a bind but we recommend the use of No.1.5 pucks and pins moving forward for all pucks kits (unless specified). 100% made in the USA! Features: large wear surface area 100% made in the USA! ****Does not work with B64 center assembly for front and rear drive assembly only ****