I keep an Ultra-Sil shopping bag in my car’s glove compartment and occasionally take it on trips with me where I know I’m be doing some local shopping. It wads up tiny but holds a load of 200+ pounds.

Sea to Summit has expanded on the idea with this nifty Ultra-Sil Daypack. It follows the same general idea: the backpack comes in a little wadded ball that weighs only 2.4 ounces (68 grams) and has a snap to clip onto a belt or strap. When you take it apart, however, you’ve got a daypack that holds 20 liters and is super-strong. Seams are reinforced and it’s made of water-resistant Siliconized Cordura.

This product enables you to add a third option to your bags without taking another bag. You’ve got your main suitcase or backpack, a smaller bag with your laptop or other gear, then this wispy one that can be your sightseeing daypack. Or it can be your shopping bag when you go out to stock up on food. (Just don’t do like I did and stuff a leaky bag of white cornmeal into it and end up looking like somebody signed you up as a drug mule.)

It almost looks like a magic trick with you unfold this instant daypack because it compresses so small that you can wrap your hand around it and obscure it completely. For reference, it’s even smaller than the Flip & Tumble ball that bag goes into. It comes in five colors and lists for $28. It may end up going for less online, but for now it’s hard to find. The Sea to Summit people say it’ll appear any day now at REI though, so search their site to check.

Get the full scoop at the Sea to Summit product page, including where to buy it at an independent retailer in your area.

Related review: Tom Bihn double-duty packable daypack