These items appear to be quite robust for their weight and as described elsewhere they appear to be more than adequate for light - medium loads which can be carried with confidence. For example, I have placed reasonably valuable items in pockets of my rucksack and secured these objects to D rings on straps using a lanyard, e.g. camera, tactical torch, keys, etc., with confidence just so I know they won't get lost if they fall out inadvertently. They would also be perfect for attaching items to belts, etc. The screw fixing mechanism appears to be tight enough to remain in place securely although others have expressed concerns in this regard. This is the only reason I have given 3 stars and not 5. I will wait and see what happens in the future with more robust use. I have, however, ordered 2 more pairs because they are such good value for money and I can simply attach them to belts, loops or webbing, etc, in case I need them in future. The additional weight is negligible and their utility far outweighs the cost of having them 'just in case'. Recommend.
Addendum(Jun'11):having bought 3 more prs of this item I would just like to add a further comment. There does appear to be a quality control issue with this item as at least 2 items have had problems with the threads which secure the screw locking barrel. One had no threads whatsoever whilst the other (in a separate pack) had inadequate thread depth which meant that barrel wouldn't lock gate properly. However, would still rate 3 stars for above reasons.
Addendum (May '12): Wilkos have now started selling very similar carabiners along with their camping goods. Slightly bigger and very similar quality. The main difference is the price - 2 for less than £2.00!!!!! Just bought a couple of packets and currently trying them out. Appear to be reasonable quality and all screw locking barrels actually work properly unlike these ones. Try Wilkos first! Good luck.