In the thirteenth century ‘Great Helms’ or ‘bucket helms’ evolved to enclose the whole head. They seriously limited visibility and were intended primarily for cavalry (who rode in tight formation with little need for manoeuvrability). Great helms fell out of use on the battlefield during the fourteenth century, though they remained popular for tournaments.
Great helms may only be worn by knights from c.1220 onwards. The helm should be worn on top of an arming cap and maille coif and may also go over a cerveillière. They may have flowing cloth decoration attached to the top of the helmet.
Helmets with movable visors only came into use in the late thirteenth/early fourteenth century.
A thirteenth or earlier fourteenth-century great helm with cloth decoration (matching the knight's heraldry, of course).