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Size: 40 mm valve (regular valve). Suitable for inner tubes of 20 x 4.0/4.5 bicycle tyres Long durability, easy storage, improved tyre durability, longer life, excellent heat resistance and very low air/water vapour permeability [More Durable] Bicycle inner tubes are made of high quality butyl rubber. It has better sealing performance, ozone resistance, anti-aging, shock absorption and electrical insulation advantages. Easy to install: installation is quick and convenient. When inflating a tyre in case of full blowing, please refer to the inflation guidelines. Replace old tyre tubes within minutes, which is time-saving and effective. The replacement of butyl rubber tyre tubes can absorb the impact on bumpy roads and thus achieve comfortable and safe cycling. It has heat resistance and can withstand wear and tear in daily use. Installation instructions: Please check the side of your tyres to understand the tyre size used by the bike