I bought it, because for my older Schagerl trumpet it was not possible to place the BERP on the instrument. It was a very good choice for me, with another feeling like the berp, because the Mack with the opened style always let full of the air, without no resistance.
One important thing is needed to know, after playing or practicing it must be taken out from the instrument. It could be easily jammed, and hard to get out.