Here is a type showing of this series, including some "rueda de carreta" specimens, two covers, and a piece. There are three papers: watermarked loops, watermarked cross-hatch lines, and unwatermarked. The stamps shown below are unwatermarked (2 cuartos and 1 real), and watermarked loops (4 cuartos and 2 reales). Quick links: types / rueda de carreta (wheel barrel cancelers) / two covers and a piece