Socket Head Cap Screw
These socket head cap screws are both for the Bridgeport 6F and 8F power feeds, and the Series II Bridgeport.
If you are looking for them for the bearing cap please verify the HP of your motor. They will work for the 4HP, but not the Series I.
If you have a Series I 2 HP or 1-1/2 HP, the item you need is the 1534. See below for the link.