The price is a significant indicator... I pay like 3-5 bucks for 5 foster slugs but 5 sabot's will be like 8 bucks on clearance sale...
If you can view the open box as cheap shells most often aren't a sealed box a foster is a BLOB that fills the diameter of the shell but a sabot will look much smaller and/or very pointed...
foster...
http://www.winchester.com/PRODUCTS/n...x?productid=66
sabot
type one
http://www.cabelas.com/cabelas/en/te...=0180101070502
type 2
http://www.remington.com/products/am...olid_sabot.asp
Brent