Clips for securing one inverted sheet pan over another for proofing bread dough, dehydrating, freezing, or anything else you might need it for. Sized to fit the ubiquitous half or full sized rolled edge aluminum sheet pans common in restaurants and bakeries, but feel free to scale it if your specific pans vary. Definitely not oven-proof with any filament I'm aware of. I wouldn't trust a dishwasher either for that matter.