A Impac bicycle tube is predominantly made of Butyl rubber.
Butyl is a very elastic and airtight synthetic rubber.
This high elasticity Impac tubes allows a wide range of different tire sizes to be covered.

Specifications:
Brand: Impac
Wheel size (inch): 16
Valve type: Schrader valve (car)
Valve length: 35 mm
Valve diameter: 10.8 mm
Maximum valve pressure 6 bar (Keep the maximum tire pressure in mind)

This inner tube is suitable for tires with INCH size:
16 x 1.75
16 x 1.90
16 x 1.95
16 x 2.00
16 x 2.125

This inner tube is suitable for tires with the ETRTO size:
47-305
50-305
54-305
57-305