The short answer for a Roborovski's sitter kit
A Roborovski dwarf hamster staying with a sitter for a week needs his own escape-proof enclosure, a deep bed of his usual substrate, his seed mix with a little dried protein, a solid-surface running wheel, a sand bath, several small hides, and a fine-spout water bottle. Robos are the smallest and fastest of the pet hamsters, and they are watched more than handled, so the packing list protects his burrows, his security, and his mostly hands-off routine.
Escape-proofing comes before everything else
Check the enclosure before it leaves your house, because a Roborovski dwarf hamster can flatten through gaps that would stop a larger hamster, and bar spacing that suits other species is often too wide for a Robo. If his home is a tank or bin-style enclosure, confirm the lid latches and any ventilation mesh is fine and intact. Move him in the enclosure itself where possible rather than a small carrier, since a week in a travel box is too cramped for an animal that runs long distances nightly. Tell the sitter to do every food and water change with the enclosure on the floor or inside a dry bathtub, so a sudden dart for freedom becomes a short recapture, not a lost hamster behind furniture.
Bedding, burrows, and the sand bath
Pack generous extra bedding of the exact type he already uses. A Roborovski builds burrow systems and scent-marks his routes, so ask the sitter to spot-clean only the visibly soiled corner and leave the rest of the week's architecture standing. Include his sand bath with hamster-safe sand — desert species like the Roborovski keep their coat grease-free by rolling in sand, and daily access matters to him. Several small hides at floor level, a bendy bridge, and a couple of cardboard tubes give him the covered routes he prefers, because a Robo crossing open ground feels exposed and will dash or freeze.
Food, wheel, and water for a tiny athlete
Send his usual seed mix in daily portions, plus the small amount of dried insects or plain cooked protein he normally gets, and note the few safe fresh extras he knows, in thumbnail-sized quantities. Scatter feeding across the bedding suits a Roborovski's foraging style better than a bowl he can tip. His wheel must be solid-surfaced — wire rungs can catch tiny feet — and sized so his back stays flat as he runs; it travels with him, because a week without a wheel leaves a very energetic dwarf hamster climbing the walls, literally. Use a small water bottle with a fine spout positioned low, and ask the sitter to tap-check the ball valve daily, since a stuck bottle is harder for an owner to spot in a pet this small.
Notes on temperament and watch-outs
Write honestly that this is a look-don't-chase pet: a Roborovski dwarf hamster is generally observed rather than handled, and the sitter should let him wake in his own time towards evening rather than digging him out of a burrow. Leave your exotic vet's contact, your number, and permission to arrange care. Ask for a call if he is seen out in the middle of the day looking wobbly, if droppings turn runny, if he is scratching persistently, or if food is untouched two nights running — in an animal this small, a day of not eating is significant, and early advice matters.
A KinsLe Care Pass written for your Roborovski lets the sitter check the escape warnings, scatter-feeding portions, and hands-off handling rules whenever needed, so his cautious little routine survives your week away.