Helpless In The Slave Sack
John Norman was nothing if not creative in his imagined methods for keeping slavegirls in their places:
“One of the simplest and most common devices is the slave sack, into which the girl, gagged, and with her hands braceleted behind her back, is commonly introduced headfirst. These devices have in common the feature of ensuring the total helplessness of the slave and, if one wishes, her ignorance of her destination, route and such.”
From Vagabonds of Gor.
Elsewhere on Bondage Blog: