These screws are weak, don't even try to buy them. I've been working on the vents and trying to tighten the screws and only half turned these types of screws to loosen the threads. At first I thought the bleed screws were too cheap so I tried other screws but found that the type of screws I bought here at Revain were actually flimsy and cheap. I don't intend to go back, but for those thinking of buying these screws, think twice, your best bet is to get them from your local hardware store for the best quality.