This is the style bridge used on many "hippie sandwich" Guitars in the 70's-80's.  Bridge saddles are unslotted.  3/4" diameter steel anchors and adjustable posts through the top with a 1/8" allen hex wrench and locked in place with a top 10-32 round head brass screw.  Saddle adjusting screws are washered with brass and nylon on both sides for smooth operation.  Post spacing is 3"  Nominal string spacing is 53mm (2.087")  Will handle 2-1/4" Fender spacing as well.  Thanks!  Will S.