I have to agree the one on e-bay appears to have a preset regulator. Comparing it to the one from automated aquarium, they appear to have different regulators. GHaving said that, i don't want to imply that its wrong, just different. With a preset regulator you can loosen the lock nut and adjust the set screw. I've used these same regulators for other purposes at work. Its sometimes nice when theres the chance it might get knocked out of adjustment, either accidentily or on purpose.. If you want to change a preset to a knob adjustment or back, you just need to switch the adjustment knob for the screw. I've even used a standard machine screw and just filed, ground or machined the end to match the blunt end off the original screw or know.