I bought some 'Slime' from Amazon which is a green substance that you put in your bicycle inner tube which is suppose to self heal punctures as you get them. US Visitors: Amazon.com: Slime Tube Sealant: Automotive UK Visitors: Slime Inner tube sealant - 8oz: Amazon.co.uk: Sports & Outdoors When ordering I had no real idea if it worked. Everyone in the reviews said its amazing and worth having but none of them actually ever mentioned if the product actually works and sealed a hole. They put it in and say a week later no punctures so it must be working and give it 5 stars, which lets be honest isn't a actual review of the product doing its job So I've had the product in for about 4 months, hadn't had any punctures that I knew about since then so I didn't know if the product works or not. However on my cycle to work today I lost a lot of tire pressure suddenly and had to pull over to investigate. Half asleep and close to work I was too frustrated to do a proper investigation so I just pumped the tire up quickly and jumped back on and raced to work hoping that whatever was releasing air would hold enough for me to finish the last 5 minutes of my journey to work (which it did). I went into work assuming I'd come out later to a flat tire, have to pump it up then race home with regular top ups of air. To my surprise I came out of work and I still had good tire pressure. So I assumed the valve or something must be playing up. Either way I raced home at the speed of light hoping the tire would hold which it did. So, to get to the point of this story. After getting home I decided to take off the back wheel and find the cause. To my surprise I found 3 holes in my tire all covered in green slime. I've attached two photos to this review of two of them. After checking my tire I found a nice sharp stone had gone through and caused a hole which explained the loss of tire pressure on my way to work, but what did happen is the slime reacted and sealed the hole allowing me to go on with my journey (with either low tire pressure, or a quick top up of air and continue onwards). But more importantly, it shows I got 2 other punctures over the 4 month period which I never even knew I had. No loss of tire pressure and no sharp objects sticking out my tires. So it happened at some point but the slime worked so well I never knew it happened. So the jist of it is, Slime works. If your like me and can't be bothered replacing an inner tube or doing a puncture repair on the sidewalk, just put slime in and pack a small pump in your bag (or on the bike frame). Slime will cover the hole, and if it was a big one which took a while to seal and you lost a lot of air, use the pump for a quick top up and continue on your way. I don't usually write product reviews, but as this has saved me so much I think it deserves me promoting the product a little!