Inner tube puncture repair sealant originally designed for mountain bikes but works well in any air filled tyres. It is ideal for air filled tyres often found in modern pushchairs and 3 wheelers.
All the instructions are on the packet but briefly you remove the valve and using the tube supplied put the slime inside the innertube before replacing the valve and re-inflating.
The tube will then be resistant from punctures with the slime sealing up most puncture holes.
It comes in a size of 8 fl. oz and should be enough to 'slime' 4 12" tyres.