"I should start by pointing out that the bore of this is only around 4 or 5mm; if you're planning on using this for a washing-machine feed or similar, then I would recommend instead that you bite the bullet and get it plumbed in properly.
Where this is extremely useful is when draining down pipes that are either air-locked or can't be drained normally for one reason or another.
Goes on easily enough with a screwdriver, then wind in with an adjustable spanner. All done, now open 'er up and let 'er flow!"
"I bought this self cutting valve to make a connection for a washing machine but the connecting point under the sink unit was particularly tight. This valve ( not my first choice for this type of connection) came up trumps and saved me a lot of hassle, and my customer some upset."
"Used this item to plumb in a basin in upstairs toilet. Access to pipework was difficult for solder fitting or compression. This item worked perfectly although I did have to open valve and push a thin screwdriver down to clear the cut section of pipe so that water would flow. Make sure that the main stop cock is turned off before trying this,"
"When this valve cuts into the pipe it bores a little hole but doesnt always cut right through so in effect, a little flap is created. this can restrict the flow - as i experienced on an outside tap - and I had to replace it for a compression fitting. If this fitting does cut clean through, the little circle of copper does go into to the pipework and could lodge in another fitting along the line thus causing a problem later on for you, so its not just plumbers trying to squeeze you for money but save you a 'possible' problem later on. Overall, its a handy wee fitting."