Id prefer to rate 3.5 but the price point gained a 4.. The average adult hiker would need 2. It inflates to around 8cm height but.. It will work if one uses a jumper underneath it to offer the extra height needed to avoid a sore neck. The valve is plastic and seem reliable and I have no issue when the valve is capped..it should be fine. The material is somewhat thin 1.2mm approx..but it's not a chair. It is ok for the price and we are talking mid range gamble. It's a bit low.. It's a bit thin.. But hey ... It will work with a bit of extra packing. It has a good small reliable carry sack.