Pocket rosaries are one decade rosaries (10 Ave beads and 1 Pater bead) with a crucifix (or a cross) at one end and a medal at the other.  Keep one in your pocket, in your purse, in your glove compartment, in your desk drawer, etc.  Your rosary will always be available for prayer.  Stuck in traffic because of a car accident?  You could prayer the rosary for the accident victims.  Stressed at work?  Take a break and say a decade or more of the rosary.