The medal has the text 'This medal represents one year of Junior Membership' around the edge.  It also has a 2 year membership bar on the ribbon which reads 'Two Years Prayerful'.

I think this dates from the 1800s but not sure of the exact year.  The Band of Hope movement began in 1847 and ran in to the first half of the twentieth century.

The medal is 3.5" in diameter.