They use a siphon design (described as "siphon technology") to maintain a continuous fresh food supply.
Refilling is done from the top — the feeder has a top lid or opening so you can add hay without disassembling the unit.
They are listed for rabbits and for all life stages (noted as Pet Lifestage: All Ages).
They are described as having a sealed construction (a seal-design) intended to prevent food leaks and to block dust ingress.