What size are those rubber o rings under vintage Starfire bass bridges?

[lungimsam]

Anyone know their size? I see them and they are different than the foam blocks under the NS bridges. Just wondering if they are rubber o ring gaskets or something on the vintage basses? They look pretty thin. Thanks.

My fretless converted NS bass's bridge gets low enough to deck the action pretty good but I like more front bridge tilt up and tail down than my NS foam blocks are affording. Thought maybe o rings a la vintage style would work easier than me shaving the foam blocks down half way.
Maybe just a trip to the hardware store and get a bunch of different thicknesses to find which thickness will be best?

UPDATE:
On another LTG thread there were reports of both rubber and felt rings (no sizes mentioned). I might go with felt as the rubber was reported on 1970 and later models, the felt on fronts '67 model. Not that it matters but felt is probably friendlier to the bass than rubber.

 

[fronobulax]

Not that it matters but felt is probably friendlier to the bass than rubber.

There are many things that look like and are called "rubber". Some of them outgas something that interacts badly with nitro finishes. See threads about damage caused by guitar stands and racks. Going with felt might be easier than determining that "rubber" won't interact with the finish in a negative fashion.

 

[lungimsam]

Felt sounds good! Thanks!!!

 

[lungimsam]

Here are the foam thingys on the NS model. I cut them in half for now to get the tail drop I need…