The Finn Plain Lead are really good for those situations where you want to add a bit of movement to your rig rather than anchoring it hard to the sea bed. The flat shape still holds reasonable well but tide pressure on the line will slowly move it along the sea bed to help search for fish and also attract the attention of flatties etc.
The The Finn Plain Lead also work well on the boat for drifting over banks etc as the flat shape does not ‘roll’ like a standard bomb lead.
Another use is for fishing with feather lures as the shape of the The Finn Plain Lead allows you to work the lures near the surface and also gives an attractive ‘flutter’ to the lures as they drop through the water.