Having read the comments of others relating to similar (green) tools almost twice the price, but also knowing that a bad workman often blames his tools, I was highly sceptical about whether an implement of this sort would work on my heavy wet clay, so opted for this cheaper model. How wrong can you be? It is well made and the welds appear strong after 3 days of use so far.
I have found however, there are precautions to take if you are to be successful and have lots of little soil cores all over the place.
Wear good gardening or riggers gloves, work the tool from side to side not backwards and forwards, have a large bucket of water and a cane ready to clear and clean any persistently blocked tube, oil the tubes with the aid of a small diameter bottle brush + engine/chain/two-stroke oil, but most important of all, keep the tubes sharp with a good flat file. The brush is also useful for thoroughly cleaning the tubes after work.