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All socks/Randy Sun

Randy Sun FLEX Waterproof Mid Calf

Mid calf. Cushion not published.

mid calf · no height published, drawn at a typical heightpadding: the maker doesn’t say where · Waterproof membrane

The footwear outline is schematic. Check the cuff with your own shoes.

View at Randy Sun ↗Compare this sock

When you want a waterproof membrane for wet trails

A mid calf waterproof sock with an ultra-thin knit and an inner layer of 43% juncao fiber.

Keep in mind: Water can still get in over the cuff, and the three layers take more room than a standard sock, so try it in your shoes before a wet trip.

Closest in Randy Sun’s range: the CORE Waterproof Ankle. They differ in cuff, weight and blend; the size chart is the same.

This sockCORE Waterproof Ankle
Cuffmid calfankle
Weightultra-thinNot published
BlendSeparate blends for each layerSeparate blends for each layer

Compare the two side by side

Materials, padding and sock type

Waterproof membrane · cushion not published

None
Light
Full
Extra
Padding shown schematically. Brand labels do not share a thickness scale.
Exact model
Randy Sun FLEX Waterproof Mid Calf
Style number
RS336 / RS341
Size chart
Unisex chart
Cuff height
mid calf
Weight (maker’s term)
ultra-thin
Cushion (maker’s term)
Not published
Cushion location
Not published
Sock type
Waterproof membrane
Layers
3
Material blend
Separate blends for each layer
Wool-free
Yes, no wool or alpaca listed
Facts from
Randy Sun’s US site

Inner: 43% juncao fiber, 43% cotton, 10% polyester, 4% elastane.

Outer: 38% juncao fiber, 38% cotton, 19% polyester, 5% elastane.

Between the inner and outer knits sits the middle layer of Randy Sun’s DROPZERO system, printed as a 100% PU membrane, PFAS free.

What Randy Sun says about it

“Waterproof-Breathable DROPZERO System”

“With a flexible, soft construction that feels much closer to a regular sock, FLEX moves naturally with your feet while providing reliable waterproof protection without unnecessary bulk.”

The maker’s own words from its product page; not tested by HikingSocks.guide.

Cushion and weight labels are this brand’s own terms. They are not a shared thickness or temperature rating.

XS
S
M
L
4.56810121415.5

US men’s

Bands follow this chart’s published ranges. XS: 4.5–6.5 · S: 7–10 · M: 10.5–13 · L: 13.5–15.5

Check the size and the shoe together

Start with the unisex chart for this exact model. Use the size lookup or the whole Randy Sun size chart to find the published range, then check the heel position, toe room and cuff in your footwear.

The maker does not give a heel-to-cuff measurement. Try the socks with your boots to see whether the cuff sits above the collar. See how sock heights differ.

Try the complete layered construction, not only one layer. Extra fabric can change toe room and pressure inside the shoe. The footwear-fit checklist explains what to check.

Care for the exact pair

Machine Washable: Turn inside out. Wash on a gentle cycle below 40°C (104°F). Use standard liquid detergent; avoid fabric softeners or bleach. Hand Wash: Gently rinse under lukewarm water to remove mud or sand. Do not wring or twist excessively. Gently press out excess water. Drying Protocol: Drip dry naturally in a well-ventilated, shaded space. Do not tumble dry, iron, or dry clean. High heat is the enemy of waterproof membranes.

Use the care lookup for this model’s wash and dry directions. A general wool routine should not override instructions for a membrane, a two-layer construction or a specific treatment.

Two socks to compare with it

Same size chart

Randy Sun CORE Waterproof Ankle

ankle · not specified. Your Randy Sun size carries over.

Compare side by side

Same cuff height

Sealskinz Scoulton Mid Length

Sealskinz · mid length · not specified.

Compare side by side

Find similar socks

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