Those plastic-like labels are factory labels.  I have seen some of the
labels in metal (same size).  They are very helpful when part of the
mechanism has to be removed for repair or restoration, and for getting
things back in the proper place.  The plastic-like labels grow fragile
with age and are prone to breaking.

I use a label printer and print them very small, and roll them neatly
on the hoses.

Bruce Clark