Summary: As with other reviews listed below, this product does indeed give off a high pitch noise. It is quite noticeable at a yard's length or less. I purchased this product from a private seller knowing this product had noise problems in its various reviews.
Pros: --- Namebrand product with trusted reliability --- High wattage capacity for servers or power-intensive workstations --- LCD screen & easy of use --- Small compact design
Cons: --- Annoying high pitch noise (See other comments listed below)
Excerpt: The flat ones, the APC 350's, don't seem to respond as quickly so these are worth the extra money. I see a lot of problems with the smaller ones not being able to respond to a quick flicker, especially with networking equipment, firewalls, modems, etc.
Cons: Sometimes the energy Master plug isn't recognized at being off or on so the slaves wont turn off when the Master is off. Resetting the system doesnt seem to fix this, it just fixes on its own. Not a deal breaker.
Summary: The sound level emitted from these is unacceptable.
Pros: LCD screen. Reliable. Good warranty and support.
Cons: About 80% of these that we purchase for corporate use at every person's PC has a very noticeable and annoying sound. The other 20% are quiet enough to not notice while sitting at the PC. I would never purchase this for home use as it would be far too annoying. Battery wiring is too tightly packed...