What we have here is a double ended etch resistant marker pen, one end is a fine point, and the other is a medium one (pcb in picture not included).

A good ink flow, good tip size, excellent adherence to copper and other materials, resistant to finger smudging, near instant drying, and of course quite resistant to etching solutions (I' using Hydrochloric Acid and Hydrogen Peroxide / Cupric Choride). Wipes clean with methylated spirits (and other solvents).

Doesn't matter if you are using toner transfer or photo etching, you will at some point want to touch up a trace or pad before etching to save redoing a whole board because of one problem, having one of these pens handy saves you time and money.

The ink lays on copper thick enough you can actually feel it if you run your finger over what you drew, and again, it dries almost instantly.

The medium point has a bit of "give" so you can actually get a range of thickness out of it depending on how hard you press and the angle you draw. Good for thicker traces and filling in ground planes. Ink really flows very well from this tip.

The thin end is good for drawing pad circles and thinner traces, it has less ink flow so I do recommend that for thin lines you do a 2 or 3 passes and be sure to hold the pen at right angles to the board, one layer of ink may not be enough if your etchant is aggressive.

These are also suitable writing on rewritable CD and DVD media, metals, plastics, glass and cloth.

See all my current listings: http://goo.gl/L40ps7

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