Schwalbe Inner Tubes for 16" and up to18" folding bicycles from Brompton (349) and Birdy (355)  are available in:
1) Presta 40mm SV4 (red) or 
2) Schrader 40mm AV4 (green)
 
Models:
16-18x1 1/8-1.35 AV
Valve Type: AV (Auto/Schrader valve)
Valve Length: 40 mm
 
16-18x1 1/8-1.35 SV
Valve Type: SV (Sclaverand/Presta)
Valve Length: 40 mm
 
Ideal for folding bikes and small city bikes, this reliable 16” & 18" inner tubes has been made by Schwalbe with high-quality rubber with an even wall thickness. Tough and durable, you can rely on it to keep you rolling mile after mile.
 
Technology:
Inflation Pressure Stability
A Schwalbe inner tube maintains the air much longer. The quality of the inner tube is already determined by its raw materials, through the ingredients and the purity of the rubber compound. During vulcanisation, each Schwalbe tube is placed in a mould and is then inflated. This is the only way to ensure a uniform wall thickness and excellent air retention.
 
Reliability
Rigorous monitoring that ensures the best operational reliability: each tube is inflated in the fabric and stored under pressure for 24 hours to check the air retention ability.
 
Tube Groups System
Due to its high elasticity and quality, a single tube covers a large number of tyre sizes. For example, tube no. 17 works just as well for 28 mm wide tyres as for 47 mm wide tyres. Only an extremely high-quality and reliable inner tube can meet this requirement.
 
Price for bundle of 2 pcs.