2 blocks are one set.
Used for shield radiation.
You can lower detection limits to stack the blocks around QSF801 for low background radiation.
Epoxy and special resin is used to coating the edge and surface of lead to prevent lead poisoning.
Size : 50 x 100 x 200 (mm)
Weight : 11.4 (Kg)/unit
It may be a little difference of size and weight by lead's feature.