They have rubber synthetics that greatly enhance one's friction on the rock.

它们是由橡胶制成的，能够增强在岩石上的摩擦力。

youdao

With special raw material (raw rubber bearing) and small friction coefficient; electricity -saving.

含特殊原料原橡胶轴承，摩擦系数小，更省电。

youdao

The large diameter super wide quality rubber wheel makes the user's ground effectively protected, and increases the friction of the brake.

大直径超宽优质橡胶车轮使得用户地面得到有效保护的同时，增大了制动的摩擦力。

youdao

Then there's the Slide (pictured above) which relies on interesting physics to support the iPad: a heavy high-friction rubber cylinder is pulled out of its tubular compartment under the metallic slope, and it can be placed anywhere on the slope to support the iPad at any desired angle, up to somewhere around 70 degrees -- you can see it and the others in action in the earlier video.

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Another major difference is that Palm's dock uses magnets to line up and secure the handset, and LG's accessory relies solely on the friction between a rubber ring and the glass back of Google's flagship phone.

ENGADGET

The intense friction degraded some of the replaceable rubber grips.

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