1 Pin Valve-Most Popular (For the small 8Gm co2 bulbs)
2 S30 Valve (For the refillable Hambleton Bard Cylinders)
3 No Valves (For no gas system, but does have a pressure relief valve)
These are good quality barrels and many people have had there's for years! You can always buy replacement tops, valves etc.
2" neck doesn't tend to lose pressure, you can't get your hand inside though.
It's actually about 45 pints so there's plenty of room for a 40 pint kit