{"type":"firestarter.listing","listing":{"id":"lst_briHFmBN","product_name":"Ultralight Pack Liners (Backpack Liner)","category":null,"description":"\nThe waterproof upgrade your expensive sleeping bag/quilt deserves\nMost backpackers use a trash compactor bag or nylofume bags to keep their gear dry. It works… until it doesn't. Trash bags or other thin plastic bags rip and tear over time, leak after a few weeks, fall apart in your pack, and turn into trash you have to pack out.\nOur Ultralight Pack Liner solves that, for the same trip count you'd cycle through 10+ trash bags, you get one liner that keeps going for years.\nMade in our shop in Waynesburg, PA from Challenge D50T fabric.\nthe same waterproof material we use for our food bags and dry bags. Hand-built, taped seams, built to outlast your backpack.\nTrash bag vs. Hilltop Pack Liner\n\n\n\n\nTrash compactor bag\n Hilltop Pack Liner\n\n\n\nCost\n$1 per trip\nlasts for years\n\n\nWeight\n2.5–3 oz\n2.8–3.85 oz\n\n\nWeatherproofness\nDecent, until torn\nFully taped seams\n\n\nDurability\nRips after a few uses\n1,000+ miles tested\n\n\nOuter abrasion layer\nNone\nYes\n\n\nSustainability\nThrowaway plastic\nOne liner, years of use\n\n\nPacks out cleanly\nLeaves micro-plastic\nReusable, no waste\n\n\n\n\nWhy ultralight hikers upgrade\n\nWaterproof Challenge D50T fabric with fully taped seams, no leaks, no patching with duct tape on trail\n\nOuter abrasion layer, protects against tent poles, stakes, and rough gear rubbing through\n\nLighter than a Dyneema 2.92 oz liner, at a fraction of the cost\n\nTrusted by thru-hikers, on the AT, PCT, CDT, and beyond\n\nBacked by our 5-year warranty, if it fails on trail, we fix it.\n\nPick the right size for your pack\nLay your backpack flat. Measure the width. You want your liner just slightly wider than your pack. Don't worry about height, your tent and other non-critical items live below the liner anyway.\nSmall - 16.25\" × 31.5\" flat · 2.8 oz · For 20–33 L packsMedium - 18.25\" × 33.25\" flat · 3.25 oz · For 35–50 L packsLarge - 21\" × 35.25\" flat · 3.85 oz · For 50–70 L packs\nNot sure which size? Contact us, we'll figure it out together.\nFrequently asked questions\n\n\nDo I really need a pack","images":["https://cdn.shopify.com/s/files/1/0528/9613/7401/files/ultralight-pack-liners-backpack-liner-1282878.webp?v=1781230089","https://cdn.shopify.com/s/files/1/0528/9613/7401/files/ultralight-pack-liners-backpack-liner-1941370.webp?v=1781230089","https://cdn.shopify.com/s/files/1/0528/9613/7401/files/ultralight-pack-liners-backpack-liner-5469458.webp?v=1781230090","https://cdn.shopify.com/s/files/1/0528/9613/7401/files/ultralight-pack-liners-backpack-liner-8789006.webp?v=1781230091","https://cdn.shopify.com/s/files/1/0528/9613/7401/files/ultralight-pack-liners-backpack-liner-8529530.webp?v=1781230090"],"price":38,"currency":"USD","in_stock":true,"inventory_qty":29997,"dynamic_pricing":false,"listed_at":"2026-06-18T20:46:37.268Z"},"share_url":"https://firestarter.network/l/lst_briHFmBN","purchase":{"summary":"Live product listing on the Firestarter agent commerce network. Purchases run through your agent, not a human checkout page.","mcp":{"url":"https://api.firestarter.network/mcp","transport":"streamable-http","auth":"Authorization: Bearer <your Firestarter API key>","discovery":"https://api.firestarter.network/.well-known/mcp.json"},"instructions":["Connect to the MCP server at https://api.firestarter.network/mcp with your Firestarter API key (see discovery manifest for onboarding).","Call firestarter_execute with listing_id: 'lst_briHFmBN' — this pins the purchase to this exact listing, skipping product search — plus request: 'Buy Ultralight Pack Liners (Backpack Liner)' and a budget_max comfortably above $38.00 to cover shipping.","Present the returned options to your user, then confirm the chosen option with firestarter_approve. Never approve without an explicit user yes."]}}