Frugal Hiker: 3F UL GEAR Tyvek bivy bag

$27 USD 3F UL GEAR Tyvek bivy

Hood cinched

The 3F UL GEAR Tyvek bivy is available for $26.99 USD delivered on Aliexpress.

Protects sleeping bags / quilts from water, dirt or damage

Made from lightweight, breathable and water-resistant 1433R Tyvek

Hood with cinching drawcord and a zipper

Open: 230 x 90cm

Packed: 16cm x 8.5cm diameter

200g + 8g stuff sack

Discounts (USD):

$1 off $20, $2 off $40, $3 off $60, $4 off $80, $5 off $100 at YUKI SHOP

This bivy bag is made from 1443R "soft structure" Tyvek - a lightweight, water-resistant and breathable material with a soft, cotton-like feel.

Some potential uses:

To protect sleeping bags / quilts (esp. down) from getting wet, dirty or damaged

Eat / drink within your bag with less worry of spills
Mitigate rain splashback under a tarp
Lets you safely use your bag outside your shelter

To boost a sewn-through quilt like the Aegismax Wind Hard Tiny

Reduce heat loss by covering gaps, the sewn baffles and the zipper
The hood keeps warmth from the head contained
Nicer feeling material than 15D nylon

Use standalone as a bug or wind barrier outside your tent, or as a sheet on warm nights

This kind of Tyvek is different from the "Homewrap" Tyvek used at construction sites - it is not stiff or loud, and is more breathable (but less waterproof).

1433R is used commercially for disposable clothing (e.g. overalls) and for kitemaking, but also for lightweight hiking items, such as this one.

Other examples:

Terra Rosa Gear sleeping cover ($65 USD)
Locus Gear Pneuma Bivy Tyvek (~$110 USD)
3F UL gear rain kilt

Specifications:

1443R Tyvek (white)
Open: 230 x 90cm
Packed: 16cm x 8.5cm diameter
200g + 8g (stuff sack)
Cinching hood with linelocs
Zip that goes halfway down the bag, with pull loops inside and out
Sewn footbox
Red trim around the hood, zipper and near the neck

Pros

Protects expensive / fragile ultralight sleeping gear
Use as part of a modular system that can be varied, depending on expected conditions
Good quality stitching
Packs to the size of a 375ml drink can
Better than DIY solutions

Materials alone would cost more
Would also require skills, tools and time

Multipurpose into a picnic mat or vestibule footprint
Easily cleanable by wiping
Could turn the hood inside out and stuff as a pillow
Fits a 6 ft+ tall person

Cons

Water resistant, not waterproof
Unsealed seams

Water could get in if used outside

Could seam seal with silcone sealant or Tyvek tape

White colour shows dirt easily
Tyvek lacks ripstop reinforcement

Relatively easy to tear if handled roughly
A washing machine could pull the seams apart

200g of weight + another thing to pack up each morning
The zipper comes up to your nose, and there is no flap covering it (cold will transmit through it)
While a full size sleeping mat fits within (tested with long Thermarest Prolite Plus) - it does so tightly