skural

Hi all.
Just had to buy this one when I saw it. It says 'Louis Curtis PERFECT' on the bell.
No serial numbers. the valves are numbered 19, 20 and 21, and there is an extra piece attached to the main tuning slide. It isn't playable yet, but my guess is that this piece makes it possible to switch tuning iei between Bb and C. Looks like a trumpet to me, but spending the last couple of hours searching the net for information I came up with nothing.

Are there anyone here that have any knowledge about what I've got ? How old it might be, and who might have made it ?

Thanks in advance.