. Maximizing education investment and collaborative learning with ultra-short throw projection the BenQ LH890UST utilizes the unparalleled qualities of a laser light source to achieve optimized performance long-lasting reliability and energy efficiency for the leading schoolsKey Product Info . Superior dustproofing design to prolong projector lifespanBrilliant display of lecture contentLaser-enabled ultra-high contrastLong-lasting high brightness Product Features Superior dustproofing design to prolong projector lifespanBenQ LH890UST is designed with DustGuard technology including sealed laser modules to protect the laser bank. This lock-and-key design hermetically seals the laser engine from dust to prolong projector lifespan. Brilliant display of lecture contentLH890UST\'s powerful BlueCore laser projection utilizes a dual color wheel system to produce outstanding color performance by increasing color ratios and purity of RGBY colors greatly enhancing color saturation and brilliancy at the same lumen output of lamp-based projectors to deliver superior viewing experiences. Laser-enabled ultra-high contrastLH890UST laser projectors create strikingly clear images with stratospherically high native contrast ratio of 100000 1 for true deep blacks vividly rich colors and fine subtle details. LH890UST also features spontaneous response requiring no wait to turn on or resume from blanking in true black for flexible performance capability. Long-lasting high brightnessLH890UST produces 4000 ANSI lumens and superior brightness efficiency at the same level as IFPs for clear sharp images and text even in large bright classrooms. High brightness allows lights to be kept on during lessons and sealed laser banks prevent dust entry to minimize brightness decay for long-lasting high brightness.