They are straightforward to use and can simply be tied on to the leader at the loop in the link but my favoured method is that recommended by the original designer of the links, Paul Hunter.
Form a loop in the end of the leader, the perfection loop gives the strongest connection.
Tie a length of rotten bottom line to the leader; this must always have a lower breaking strain than the main line and should be around half the strength of this reel line. The Uni knot is the most effective way of securing the rotten bottom behind the loop.
Hang the loop over the circular section of the canny link and using a key ring or scissors handle on the bottom leg of the link pull the link onto the loop.
Tie the weight to the end to the rotten bottom and before casting hook the lead onto the bottom leg of the link.
The free top leg on the link can be used to clip down a hook snood. These links, like most rotten bottom links are not totally secure and care should be taken when casting. They are not suitable for Pendulum style casting.
The links are widely available from TronixPro stockists including Veals online.
Paul's original video on using the links can be found here.