This switch will fit the following models:AR01, AR02, AR03, AR05, AR09, AR20, AR21, AR29, AR30, K9, K9 Mk2, DM001We have been using these switches for years in both our refurbished machines and Gtech repairs. We stand by their quality.We will not simply sell a poor quality item to match on price. We instead sell top quality items at a fair price. Just because they look the same, do not mean they are the same high quality as ours.There are plenty of guides online on installing the switch. The item does need soldering, so please only buy if you are a competent solder user. If you are having the following issues; machine will not turn on, machine will not turn off, machine button has to be pushed a few times to work, or you have to push really hard. These are all good indications that the switch is at fault.