SP-1 is another unusual design. I don't think they had that before. Both are nice. The price, too, was good --- $620 for SP-1 and $670 for the other.

SP-1 still available at the Chops website:

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i was just reading about that
i think @iusedtoberich had some ...i think i saw that in an old thread...................Edit : it was not @iusedtoberich see post below
hope this helps
good luck
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The KU bumper is a specific type of rubber bumper historically used on Brunswick pool cues, known for its distinctive brown color and design. It is often sought after by collectors and restorers, particularly for vintage cues, as it differs from the lighter reddish-brown bumpers sold by other retailers like Muellers. For those needing a replacement, the Prather brown bumper (part #R15) is noted as being identical in size and appearance to the original KU bumper, and it includes a metal washer similar to the original. These bumpers are typically installed with a screw and washer, and the bumper itself covers the screw and washer, securing the cue's butt end. While the original KU bumper is no longer commonly available, similar replacements can be sourced from specialty cue suppliers.

David in FL said:

There may be others, but that's of the very few rules that I can think of where CSI and WPA rules differ...

Click to expand...

Ball in hand on a the 8b break in CSI vs behind the line (WPA) is another notable one.

And now WPA is always all ball fouls.