"Used these to adapt to female tap flexi hoses. Worked really well, with the male end of the coupler sealing perfectly onto the flexi's flat rubber washer. I assume this seal will last..
But I did have trouble holding the body of the coupler while tightening the compression nuts - due to the pointless feature of the round flange against the hexagonal section - you can't get a standard adjustable spanner into the gap between this and the compression nut. I had to file off two flats - easy enough; it's brass!"
"The male threaded part has a flat ground end suitable for sealing against fittings which use a flat washer as found on flexi tap connectors (the oppostie end to the tap) and others. The other end is a standard compression for connection to 15mm pipe. Actually slightly cheaper here than on "rival" sites!"