Biscos are made by Lamello and are intended to be used alongside either the Tenso or Clamex for joint alignment on long runs. Colonial Saw carries them, not difficult to obtain.I've never seen those? There are plastic ones available, to be used with Corain (and other brands of solid surface material.
The Lamello alternative I am aware of is the one called Bisco. They are intended to fit into the wider slot, produced by the Zeta P-2. For some reason, they are very difficult to obtain though. I don't know why?