These Cord Retainers consist of two parts, Cover and Tube..
Easily adjust tension to prevent slippage during travel.

Example: Qty. 12 means you will receive 12 Covers and 12 Tubes.

See second photo
Left Image - shows the 2 part retainer.
Middle Image - shows blind cord placed into Tube.
Right Image - shows cover placed over blinds cords and placed into tube.
Screw a cord tensioner to the wall.
Repeat with the other tensioner, But don' tighten all the way.
Now pull on one cord to snug up the cord.
and finish tightening the screw in the tensioner causing the cord to be
securely fastened.

Put just enough tension on cord so blind will operated without over tensioning.
The tighter the tension the faster the cord will ware.