▁as ▁well ▁as ▁those ▁of ▁the ▁German ▁system , ▁the ▁deep ▁t ones ▁are ▁finger ed ▁with ▁the ▁right ▁thumb . ▁Like wise ▁in ▁the ▁case ▁of ▁instruments ▁of ▁the ▁French ▁system ▁manufact ured ▁by ▁German ▁manufact ories ▁( Her bert ▁W url itzer ; ▁Schw enk ▁& ▁Seg gel ke ; ▁Le it ner ▁& ▁Kra us ). ▁Where as ▁the ▁bass et ▁clar in ets ▁of ▁the ▁French ▁system ▁of ▁other ▁manufact ories ▁( B uff et ▁C ram pon , ▁France ; ▁Back un ▁Musical ▁Services , ▁Canada ) ▁are ▁equ ipped ▁with ▁two ▁additional ▁keys ▁for ▁both ▁little ▁fingers , ▁with ▁the ▁exception ▁of ▁the ▁Canadian ▁manufact urer ▁Stephen ▁Fox , ▁where ▁both ▁finger ▁techniques ▁are ▁combined ▁( the ▁right ▁thumb ▁and ▁the ▁small ▁left ▁finger ), ▁see ▁description ▁and ▁illustr ation . ▁The ▁bass et ▁t ones ▁are ▁easier ▁to ▁play ▁with ▁the ▁last - ment ioned ▁finger ▁techniques ▁than ▁with ▁the ▁historical , ▁respectively ▁the ▁German ▁f ing ering . ▁▁▁▁▁▁▁▁▁▁▁▁ ▁Because ▁Moz art ' s ▁clar inet ▁con cer to ▁is ▁so ▁important , ▁the ▁bass et ▁clar inet ▁is ▁quite ▁an ▁interesting ▁instrument ▁in ▁spite ▁of ▁its ▁small ▁applic ability . ▁For ▁the ▁con cer to ▁the ▁extension ▁must ▁be ▁chrom atic ▁and ▁the ▁shape ▁of ▁the ▁V ienn ese ▁bass et ▁horn ▁is ▁not ▁suitable ▁for ▁this . ▁It ▁has ▁long ▁been ▁unclear ▁how ▁this ▁instrument ▁might ▁have ▁looked . ▁ ▁In ▁a ▁library ▁in ▁R iga ▁in ▁ 1 9 9 2 ▁program