You receive 2 face plates, one 4" and one 6".  Both are threaded 1"-8 Tpi.  The Shopsmith 5/8" - 1"-8 Tpi is included.  

Priced separately the cost would be around $85.

These items are not Shopsmith brand. But using the adapter makes the faceplates fit your Shopsmith perfectly.  The adapter can also be used with 1"-8 Tpi lathe chucks..