While I often cut my own 2.5" X 3.5" ATCs out of 110 lb card stock and watercolor paper for class projects and to make promo cards, I have picked up a few commercial packs for their convenience and to try different paper stocks.
Recent addition to my supply of Artist Trading Cards: Sketchbook Central's 100 lb Super Smooth ATCs pack of 25. Their surface readily accepts graphite and ink and performs quite well for rendering fine detail. When short on prep time, I use them in class for drawing the cut out characters of pop-up cards. Fine tip pens work well with them.Utrecht Design Markers for live drawing on ledger size (11" x 17") paper, we have added them to the pool of art supplies used in my cartoon sketching classes. The chisel nib can yield strokes of uniform thickness by simply turning the nib. Its brush nib is quite firm and can produce a nice variety of line thicknesses by adjusting the pressure. Found I had to reign in my drawing hand a bit, for its stroke turned grey when I moved too fast. Already started practicing on an oversize marker pad to explore its expressive range and find the optimal sketching speed to get the denser black marks. Good value choice for a double ended marker. Made in England.