This Excess Ultra Light Tube is so light you won't even feel it in your tyre. At an insane 32 grams, this 20 x 1.40-2.50 tube has a 40mm Presta valve (French valve) which will be long enough for any alloy rim and most carbon rims, unless they are particularly deep dished. 

Manufactured from Thermoplastic Polyurethane means that they are both lightweight and durable. These are a performance component though and suited for a BMX racing track, not an everyday riding around tube.