Polaris 2015 RZR 900 Owner's Manual page 108

MAINTENANCE
Brakes
The front and rear brakes are hydraulic disc type brakes activated by the
brake pedal. See page 35.
Always check brake pedal travel and the brake fluid reservoir level
before each use of the vehicle. When applied, the brake pedal should
feel firm. Any sponginess would indicate a possible fluid leak or low
brake fluid level, which must be corrected before riding. See page 108
for brake fluid information.
If you discover any irregularities in brake system operation, including
excessive pedal travel, contact your dealer for proper diagnosis and
repairs.
WARNING! Operating the vehicle with a spongy brake pedal can result in loss
of braking, which could cause an accident resulting in severe injury or death.
Never operate the vehicle with a spongy-feeling brake pedal.
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