The items itself is "UNI-T Kelvin Multimeter Leads Probes Clip Meter Test Line Cable for UT612/UT611" from ebay at about £9
The leads in the photos are definitely not "Kelvin" leads. Also, the UNI-T UT612 does NOT have Kelvin inputs - as I discovered only after receiving my meter today.
The leads in the photos are simply "screened" leads (looks like RG58U) with the outer screen cut short of the component test clip and ending in an open circuit. The banana plug connected to the screen is plugged into either one of the guard sockets on the UT612 - both guard sockets are connected to the common or ground plane inside the meter.
Kelvin leads have both conductors on each of the +VE and -VE test leads ending in a short circuit at the component test clip. One wire in each of the leads is used to drive the test signal into the component under test and is usually of heavier gauge conductor than the sense wire. The sense wire carries virtually zero current (and can be much lighter gauge) and merely "senses" the voltage across the component (for processing in the meter) and therefore imposes no additional loading across the component.
Some Kelvin leads advertised on Ebay have a fairly substantial alligator clip on the component end with the drive wire connected to one jaw and the sense wire connected to the other jaw. When the jaw is opened there is no electrical connection between the two wires but when the jaw is closed or clamped onto a component being tested both drive and sense wires are electrically connected together.
The Ebay advertisements falsely claim that they are suitable for use with the UT612/UT611 meters. Well, they can be used, as long as you don't plug any leads into the guard sockets - which makes them worse than single wire test leads due to the capacitance of the unused lead wires dangling in the air. So if you feel it is necessary to go 4 wire with the UT612, the best alternative is to use screened leads as per the photos.