7mm x 5mm Barrel Shaped String-On Clasp w/Silicone Grommet.
 
The SOC 2 String-On Clasp is barrel shaped and has a 2mm opening in the Silicone grommet that securely holds the cording that you thread through it. The outside barrel is made of hypoallergenic brass, electroplated and nickel free.
 
Basically, a string-on clasp is a stopper bead and the soft silicone grommet won't damage any of your jewelry making materials.
 
The opening will best accommodate any cording that is 1mm in width. 
 
Use with 1.25mm Beading Chain Ch-874