Picture hanging systems make use of cords to hang pictures flexibly and without tools or nails. The cords can be hooked easily into your picture rail at any spot along the rail. Picture hooks can then be slid over the cord to hang your pictures.
Perlon is also called Nylon 6 or polycaprolactam. It was given the trademark Perlon in 1952. Its fibres are tough, wrinkle-proof, elastic and highly resistant to many chemicals. Perlon can handle very high tensions, which makes it a perfect material for picture hanging cords. It's also used for other applications, such as bristles on toothbrushes and strings for acoustic guitars.
The standard, uncoated steel cable can carry up to 44 lbs. The coated version (available in the color white) can carry up to 22 lbs.
The steel cable consists of several strands of steel wire, twisted into a helix. Steel cable is especially secure as flaws in any of the wires are compensated by the other wires making up the steel cable. In short: the safest way to hang your pictures and paintings.