Johnson & Johnson on Thursday said it has voluntarily withdrawn 300 of its Cypher stents from the US market after determining that the coating on six of the devices did not meet specifications.

The Cypher stent is a tiny wire mesh tubular device that props open surgically cleared arteries. It is coated with a drug that prevents the arteries from reclogging with scar tissue.

“There is no safety issue,” said company spokeswoman Terry Miller. “We are committed to quality and are being overcautious.”