I was unsure whether to buy this, however, so far, its proved good value for money.NOTE: - when putting it together, use proper spanners to get a tight fit (not the 'free' and flimsy pressed-steel one provided). I also chose to use PTFE tape on the joins, I am not sure if that's actually necessary but I had PTFE tape (which is cheap anyway) and it made sense to use it.You will also need an adapter for whatever it is you are charging.So far, so good, 45 pumps brings the pressure back up to 'full' on my HW100 - that's about 4 mins of effort. Bending the knees to apply body weight helps. I also ordered silicon oil to make sure the pump stays lubricated (£8)All in all, for my needs of 'plinking' about 50 shots a day, the pump is better than £200 on a reservoir tank and trips to have that filled back up. Its small and folds flat for storage.