Grab the right tube for your 700C tire, just choose the valve length and tube size!
When it comes to valve length:
40mm valves are ideal for 10mm - 30mm deep rims.
60mm valves are ideal for 30mm - 50mm deep rims.
80mm valves are ideal for 60mm deep rims.
And for tube size:
Check your tire's sidewall to determine its size - then choose the tube whose range includes it!
For example: a 700Cx28 tire will work with the 700Cx25-32 or 700Cx28-32 tubes.