Korda Carp Leads - Square Pear Swivel
These leads were deigned after filming Underwater Part Four. Without any doubt, when fishing on a hard gravel bottom inline leads hook the carp quicker than swivel type leads. The reason for this is that the fish always pick up the lead from the heavy end first, because the hook link is always attached to the heavy end of the lead.
In the case of Korda inlines the swivel is actually semi-fixed inside the lead, exaggerating the 'instant bolt' effect. What Dan set about doing after watching the fish hooking themselves on Part 4, was to design the most condensed shape of lead possible. So, a fish would have to move the minimum distance before it felt the full weight of the lead.