i first tried these interchangeable knitting needles in feb this year and find them invaluable..
its like knitting with circular needle..need to change sizes you just twist off existing tips and screw on new ones..be sure to use little turnkey included or ends will come loose..
these needles are handy as they come in case and much safer to carry knitting around than ordinary long needles..i roll my knitting up and ends dont stick through knitting bag..
easy to store
price of around £35 SEEMS EXPENSIVE AT FIRST BUT YOU NEVER NEED ANY MORE NEEDLES..MOST SETS EVEN INCLUDE CABLE NEEDLLE