Gammill, A-1, Nolting, Prodigy, and most other quilting machines have a hopping foot with a 1/2" diameter (So the distance from the needle to the outer edge of the hopping foot is 1/4").
APQS Millennium has 2 hopping feet available. The standard tapered foot requires the snap on plastic adapter before you can use the acrylic rulers with it. This makes the diameter of the foot 3/4" so it requires a larger cutout for the hopping foot and any alignment lines need to be etched differently. Rulers specifically designed for this foot are labeled APQS with a 3/4" foot. The APQS Millennium has a new hopping foot available that is 1/2" in diameter. This foot requires the same cut for acrylic rulers as Gammill. So if you are ordering for an APQS, please specify which hopping foot you have.
Nolting requires two different thickness' of acrylic. The Noltings that were manufactured prior to 1995, require an acrylic guide that is at least 3/8" thick because the hopping foot had a wider range of motion. Acrylic guides/rulers designed for this foot are labeled pre-1995 Nolting. The newer Noltings have reduced that range of motion, so if you have a newer Nolting, you can use the same rulers/templates as the Gammill. Check with your dealer to verify which version you have.