Various Manufacturers 24 x 1-3/8 (32-540) Inner Tube

24" x 1 3/8" / 24 x 1 1/8" / 600 A"
This is a size used on some juvenile lightweights, early Terry bicyles and imitators, most wheelchairs.
Frequently confused with the 520 mm size. Note that both 520 and 540 are sometimes labeled 24 x 1 1/8".

Available in Schrader (standard) or Presta (narrow) valve.