Polyproline helix model, from the sequence (Gly-Pro-Pro)5.  Constructed by extracting a portion of the structure from PDB 1K6F.  Includes side chains represented as sticks, as well as the "cardinal" backbone representation to more accurately follow the atoms in the backbone within the ribbon.  Prints especially well at 3X size, for use in the classroom to aid students in learning secondary structure relationships.