Interface Essential

Business

Images Photography

Money Shopping

Programming

Computer Devices

Phone

Mail

Map Travel

Food Drink

Nature Ecology

Entertainment

Shipping

Culture

Health

Work Education

Artificial Intelligence

Arrows

Streamline 3.0

Ultimate

Core

Flex

Sharp

Plump

Micro

Freehand

Streamline Material

Nova

Cyber

Streamline Vault

Logos

Pixel

Google Material

Tabler

Remix

Feather

Iconoir

Carbon

Solar

Lucide

Brand Logos

Bootstrap

Atlas

Unicons

Ionic Icons

Phosphor

MingCute

Font Awesome

Majesticons

Mynaui

Radix

Heroicons

Flagpack

Outlined Line - Streamline Material Free

Arrow Insert

UI Actions

Rounded Line - Streamline Material Free

Sharp Fill - Streamline Material Free

Arrow Top Left Fill

Arrow Back 2

Ultimate Duotone - Free

Arrow Right

Arrows Diagrams

Flex Gradient - Free

Download Arrow

Core Flat - Free

Arrow Up 1

Sharp Line - Streamline Material Free

Ultimate Bold - Free

Guidance – Free

Up Arrow

Core Flat

Triangle Arrow Left 1

Single Triangle Arrow

Core Duo

Line Arrow Left 1

Single Line Arrow

Core Solid

Sharp Line - Streamline Material

Arrow Downward

Rounded Line - Streamline Material

Big Arrow Right

Outlined Line - Streamline Material

Nova Line

Refresh Arrow 2

Synchronize

Line Start Arrow Notch

Text Formatting

Arrow Outward

Arrow Upward

Arrow Forward

Cyber Line

Arrow UP

Keyboard

Arrow Split

Outlined Fill - Streamline Material

Line Start Arrow Notch Fill

Ultimate Duotone

Arrow Left

Ultimate Bold

Arrow Left 2

Ultimate Regular

Cyber Duotone

Arrow Down

Ultimate Colors

Plump Pop

Arrow Vertical

Plump Duo

Platinum

Right Arrow

Basic Arrows

Core Remix

Freehand Duotone

Arrow Right 2

Arrow Up 2

Arrow Next

Left Arrow

Arrow Up

Arrow Back

Arrow Shift

Arrow Down 2

<p>Flex is a fluid icon family inspired by nature's curves. The Solid variant features smooth, filled shapes with rounded edges for a friendly, organic aesthetic.</p>

Flex Solid

**Summary**: Flex's impact sub-style — opaque fills on fluid organic silhouettes, providing strong visual presence while preserving the flowing, nature-inspired quality that distinguishes Flex from geometric solid sets. Organic silhouette edges soften the fill hardness, keeping the register modern and grounded rather than authoritative or cold. The tone signals organic groundedness: "we are grounded and solid without being rigid." Best for active and selected states paired with Flex Line, feature callouts in lifestyle and consumer apps, photography-heavy layouts where organic icon silhouettes complement imagery, and navigation where Flex Line is too fragile at small sizes.

**Last updated**: 2026-04-23

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## Fit & Recommendation

### Primary use cases

- Feature callouts and primary actions where the organic filled silhouette creates distinction
- Navigation in apps where Flex Line is too fragile at small sizes
- Badge, tag, and indicator systems with a modern organic aesthetic
- Photography-heavy layouts where organic icon silhouettes complement imagery
- Active and selected states paired with Flex Line for inactive states

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## Brand & Cultural Identity

### What it communicates

> "We are grounded and organic."

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## Visual & Technical Specs

### Visual properties

| Property | Value |
|----------|-------|
| Stroke weight | None |
| Fill | Opaque fill with transparent cutouts — background visible through cutout areas |
| Corner treatment | Smooth rounded organic silhouettes — shapes flow rather than contain |
| Color | Monochrome |

### Emotional Scores

Flex Solid is one of the friendlier sub-styles in the catalog in a grounded way — solid black fills on organic silhouettes read as modern and natural, with the warmth of flowing shapes partially offsetting the coldness of a black fill. It is somewhat soft — solid fills add visual weight, but organic silhouette edges soften the overall reading. It is somewhat friendly — organic solid silhouettes are modern and considered, landing between warmly approachable and formal. It is somewhat playful in a restrained sense — the organic quality reads as natural rather than playful, with the solid fill giving authority without severity. On its human↔mechanical character, it is one of the more human-feeling sub-styles in the catalog — organic silhouettes read as natural forms, and the fill does not mechanise them.

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## Pairing & Compatibility

### Typography pairing

- **Primary**: Plus Jakarta Sans SemiBold — weight-appropriate for solid fills while retaining humanist warmth
- **Alternative**: Outfit SemiBold — modern, clean, compatible with organic silhouettes
- **Body**: Inter Regular or Mulish
- **Avoid**: Heavy grotesque display at maximum weight — overwhelms organic solid silhouettes


<p>Flex is a fluid icon family inspired by nature’s curves. It favors smooth, flowing forms. More organic than Core and subtler than the chunky Plump. Read about the <a href="https://blog.streamlinehq.com/flex/" rel="noopener noreferrer" target="_blank">design process</a>.</p>

Fluid icons

Line Arrow Curve Left Up

Line Arrow Curve Left Up icon - Flex Solid Set

Download Line Arrow Curve Left Up SVG vector or transparent PNG icon in Solid, Bold, Glyph style(s) for Sketch and Figma. It belongs to Flex Solid vectors SVG collection.