Tie tacks: pins size is 4.5 mm in diameter, 8 mm in length; Clutch backs size is 11 mm in diameter, with silver color, small and low profile Durable & Secure:Tie tacks is made of nickel plated brass. Metal material makes it anti-wear. And these are incredibly sturdy and secure. No tools required: butterfly clutch with spring fastener slices allow you to install and remove it easily, handy and convenient for use. Great for pins keeps a tight hold on them. Widely Application: Good supplies for making DIY crafts and can be applied to tie tacks, badge insignia, citation bars, service bars, name tag, toy pins, and jewelry making. Package including: There are about 100 Pairs butterfly clutches. Enough for replacement to your torn or lost one, also as good making supplies for making DIY crafts.