I'm not versed on the model numbers but here it goes. I have a closed reed jackrabbit and cottontail that have worked good for me in the past. I have both regulator open reeds. The green one (can't remember the #) locked up on me a couple times in the field and I have not used it much since. I am sure it just needed a cleaning or something. The black regulator #14 with the thicker reed has not locked yet. To be honest I have not used either of the regulators enough to have a valid opinion of them though. Basically it is a mouthpiece off their howler. I bought a Mega-Howler years back. The one that looks like a tranny funnel. It was way too big to be useful. Sat on the shelf for a couple years then I decided to "chop" it down in length. I cut about 80% of the funneled portion of the call off. Best thing I ever did. Still sounded a little funny though. I cut a reed that was about the same shape as a Regulator or AP-7 for it. It is now the best dedicated howler I own. Also when I first started howling I had a primos closed reed howler. Don't know if they make it any more but it was a great closed reed howler. Pretty high pitched. I had excellent luck with it. Hope this helps.
Later, Curt
[This message has been edited by Curt (edited 11-09-2001).]