Tube 26 x 1.5/1.75/2.10/2.125 DV

Dunlop valve (also called regular).
Fits these sizes, among others:

40-559	26x1,50	26x1,50
44-559	26x1,60	26x1,60
47-559	26x2x13/4	26x1,75	650x45
50-559	26x1,90	26x1,90
54-559T	26x2.0	26x2.0	650x50
57-559	26x2,125	26x2,125