Anti-glare screen guard for LED monitor

are there any anti-glare screen guard available in market for LED/LCD monitor?? some friends told me that its not necessary to use anti-glare in LED, but then why DELL monitor's are coming with in-built anti-glare ??

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if anti-glare screen is available for LED, where can i purchase it in KOLKATA?? what is the price?? please anyone reply....