This pair of chalkboards are blank on both sides.  The boards measure 50 cm x 32 cm (about 20" x 12") and take the chalk very well, however we recommend conditioning them before your first use by simply rubbing them all over with chalk dust.  They will get even better with more use.  Also available is Chalkboards Set 1 (single lines) and Chalkboards Set 2 (double lines