Rear wheel cylinder kit with 0.6875" bore size. First appeared in 1974 on single line 1275GT cars and then on some split diagonal until 1976. Also fitted to Innocenti cars when they had a unique 4 way switch union--Wheel cylinders for these GWW1129
The other 4-way valve on the bulkhead on later cars (part number FAM7821) is frequently wrongly identified as one of the above as they are similar. However, this unit does not have the electrical connection, and has a cylinder sticking out one end. This IS a brake pressure regulator, only fitted to front/rear split systems as far as I'm aware. The PDWA is built into the master cylinders in these applications.