High Quality:- Made of durable metal with copper/zinc/nickel, rustproof, anti rotation, durable and long service life. Reusable and easy to install:- Simply to set the picture hooks on the wall with nails, the invisible appearance makes it easy to remove and reuse. When removed, there is no mark on the walls or frames except for a small dot. Box of 20pcs+40pcs screws (weight: 162g) Box of 30pcs+60pcs screws (weight: 228g) Box of 50pcs+100pcs screws (weight: 371g) Great Organization:- Hang paintings includes small screws (no general nails), come with a plastic box, not only keep all hooks well organized, pictures also portable and reusable . Wide Use:- Suitable for hanging heavy mirrors, pictures, pictures, paintings, canvases, publications, wall clocks, etc.