Lee's Collet Die Set includes a Collet Die that uses a collet to squeeze a mandrel creating a precisely aligned case neck while reducing run out, Dead Length Bullet Seater Die, Shell Holder, Powder Dipper and instructions/load data.
Specifications:

Type	Collet Rifle Die Set w/Shellholder
Caliber	257 Roberts
Die Type
Die Series	Collet
In Set	2
Metal Type
Adapt to Mfg
Shell Holder	Included
Shell Holder Cap