Bell Standard and Self Sealing Bike Tubes Mold cured rubber for consistent side wall?prevents high pressure blow outs High quality, reliably tested inner tube Tube Weight - 110g Valve type length: Schrader; 35mm with cap Great for kid bike tires Tube Size First and foremost, you want to make sure the tube fits your tire. To determine the size you need to check the side wall markings on your tire where you?ll see two numbers separated by an 'X'. The first number refers to the tire?s diameter. The second number refers to the tires width. Select the tube that has the exact same diameter as your tire. Your tires width should fall into the range of widths listed on the tube packaging. Valve Type Standard (also called Schrader) valves are the most common valve type for bicycles. This short, sturdy valve is also used on car tires and other inflatables. Presta valves are typically found on performance road and mountain bikes. They have built-in valve locks which you twist to open before inflating. An easy way to remember is: 'S' is for Standard (Schrader, Short, Sturdy) and 'P' is for Presta (Performance, Premium). All inflatable tubes are subject to deflation from mis-installation and certain hazards. Flat Protection Finally you?ll need to choose whether to go with a standard or self sealing tube. Standard tubes are fine for most riding conditions. Self sealing tubes have liquid sealant inside that provides an extra layer of flat protection by sealing holes up to 1/8 of an inch instantly while you ride. It doesn?t get much easier than that!