Our Head Toy Elf, Duncan, has created hay mangers with NO glues, No screws, NO nails. Just safe wood, and safe rope. These are just the most small-animal friendly mangers in existence! 2 sizes: Small: works for mini-lops, mini-Rexes, and other rabbits under about 6 pounds. Guinea pigs are hay monsters so really should go with larger size. Large: works great for guinea pigs and buns over 6 lbs. Remember: you want your animal to EAT a nice compact pile of hay about the same size as their body EVERY DAY. PS: these mangers work very well over a litter box.