Just a basic ballpoint pen
If you click on the images on www.poletaevart.com/shop and zoom in, you can see the strokes of the pen. There is one image on "Shop" that doesn't have preview, but the rest do.
Also, if you are interested, see my March Feature article on The Ballpointer, I speak a little about the art, techniques and the direction of my cityscape series. http://www.theballpointer.com/archive.html
Thank you
-Andrey
www.poletaevart.com