Sydien Flat Head Upholstery Tack Home Furniture Decor Tack Upholstery Nail Pushpin Thumb Tack Silver Tone 100pcs (11mm x 17mm)

Is it made of ferromagnetic metal ?

What is the diameter of the pin the pointed nail part?

Would a magnet stick to the heads of these thumb tacks since they are iron? I'm interested in the 19mm x 23mm, but need magnets to stick to them.

Cant tell if this is a matte, brushed or polished finish? Do you have more pics or can you confirm?