It has been customary, in the Christian tradition, to produce holy cards or prayer cards, small, devotional pictures for the use of the faithful . Generally they are smaller than a playing card in size, to fit inside a Prayer Book or slip into a pocket, wallet or purse. The picture usually depicts a religious scene or an image of a saint, with a prayer on the reverse, often with an indulgence for its recitation.The circulation of these cards is an important part of a long tradition of devotion amongst Roman Catholics, with some cards, hand-drawn and coloured, having been produced since medieval times and, in modern times, printed prayer cards have also become increasingly popular amongst the Orthodox and Protestant tradition, although with regard to the latter, biblical themes are represented as opposed to pictures of Saints. It is a growing tradition, developed in the 19th century, that some cards contain a tiny piece of cloth which has been touched to the Holy Relics of a Saint, whether bone, clothing or the Shrine in which they are laid. This practice follows a New Testament tradition of preparing handkerchiefs or cloth to distribute amongst those who were sick or needed spiritual comfort.