This gadget appears to have been around since 2012
http://www.kmnautisme.com/shop/en/karver-shop/2357-handle-kjh-karver.html It's much cheaper shipped from France than from the UK (eg from Allspars).
Handling string up to a maximum diameter of 10mm, it grips everything that I've tried it on, including 4mm Dyneema. Used in conjunction with a handy billy or even without one, it's possible to apply significant tension to the jib halyard. It's an excellent but costly alternative to a potentially slippy rolling hitch or tricky icicle hitch and can also be used to get a grip on thin (and therefore uncomfortable) jib and spinnaker sheets. No need for a winch with one of these.
