Saw a set of horns on EBay listed as “Airchime RC5”
They look like K5LA’s, but when I contacted the seller, he said they were different.
Two photos were used and the price seems a bit too low for a real K5, so I’m wondering now what are the differences 
Only video I could find on youtube was this one mounted on a forklift
Ah yeah I’ve seen these ages ago … some mob which essentially cloned the microprecison design. I used to have a link to the website somewhere - will take a look.
Here you are… this was them
http://www.usatrainhorn.com/
and… obviously associated with this
http://rcinvestmentcasting.com/
Ahh, so they’re knock offs
Anyone ever do a comparison with the real deal?
Are the diaphragms and whatnot compatible?
The folks over on the horn and whistle board are not impressed for the most part. As far as i can tell.
Who know’s what they’ve done. They obviously do small run custom casting of various sorts at their shop, so it looks like they’ve taken a K series apart and made their own version - perhaps with some minor alterations to avoid getting sued for copyright. The design is pretty old so they may be clear of those laws - not sure. You’d have to check with them to see if parts such as gaskets and diaphragms are interchangeable. My guess would be yes.
Nothing that would tempt me I have to say. The price isn’t that much cheaper than a genuine Airchime (albeit 2nd hand vs new).
Contacted them asking how they compared to the real deal and this is their response:
They are similar in design but the diaphragm design is different from the original nathans. These also come with a lifetime warranty against manufacture defects for as long as they do not endure physical damage. If you have any questions please feel free to contact me directly a (786)-xxx-xxxx for any other questions. please visit our wedsite for videos and other products.
they sound louder then the original because we added extra resistance in the diaphragm housing in the back side of the trumpets. Thus requiring more air to sound them off and in turn making the sound louder with more depth of tone from each individual note.
There was a guy close to me on clist that was selling the RC3 the “k3la” clone. and i asked him to send a video of them working and they had a higher pitch tone to them compared to the real k3la.