I got this Heckel 10,000 over the summer of 2015 and it has a few odd features.. The Ab/Bb trill in the “clutch” style. This allows the system to be engaged or disengaged by a switch on the boot joint. The issue is that with the system engaged, fingering a high Ab will open the trill key. Another odd feature is above thumb Bb there is an alternate for the front C# trill key. A key with so little purpose that some people order their bassoons without it.