Wow, serious old school Krypto.

The silver piece totally reminded me of these aftermarket doodads that looked like the silver piece but had the cylindrical sleeve on either end and was made to eliminate free space when using a U-Lock. They were fairly common in the early 90s and called Bone something Dog Bone, I dunno.

You'd basically lock your bike to a rack or parking meter but before putting the bar on the U, you'd slide a couple of these "bones" on to keep everything snug and leave no room for jack insertion.