Per 
Item #: SCP [####]
Object Class: Euclid Keter/Safe
Special Containment Procedures: The entity is to be monitored every other hour to study its behavior The entity is to be in containment with no access to any living entities as it appears to only be functioning when used by living entities, while not in use it is to be ignored unless motion is detected.
Description: The entity is a 40mm wristwatch of unknown origin that can allow the wearer to manifest powers of time mastery while utilizing it, meaning that the user can accelerate and decelerate time in a 12m circular diameter as they so wish.
When used by personnel to increase the speed of time, the user becomes exhausted and the user’s body feels lethargic while decreasing their heart rate down to a minimum of 40 bpm, which is the average sleeping heart rate. On the other hand, when used to decrease the speed of time, it seems to give the user energy and increase their heart rate with the highest recorded heart rate after utilization of 232 bpm.
If this object is in use by any type of living entity other than personnel specifically requested to do so, the watch is to be destroyed, however, the entity still has use to the foundation and is to be used in dire situations that require a second chance, such as a containment breach of a powerful SCP.
SCP [####] is off-limits to testing and/or usage as after usage of SCP [####] in, either way, to accelerate or decelerate, the result of these tests has remained the same, death within a week.
From what the foundation has gathered, SCP [####] is a self-harming tool that is only to be used when the subject is faced with a death that is in the near future, or the foundation is under risk of being demolished by any unavoidable means.
Test A - 12/20/2012
Subject: Attempt to slow time using the entity
Procedure: Allow D-Class Personnel to use SCP [####] to slow time
Results: Subject is energetic, says that they "could run a 5 km marathon and still have excess energy", heart rate is accelerated to 187 bpm, as if the subject had just finished an anaerobic exercise. Muscles are slightly torn.
One hour after the usage of SCP [####] lead to irreparable bone damage. The subject later fell under the pressure of their own body weight and is now in a coma.
48 Hours after the usage of SCP [####], the subject has experienced a heart attack and their lung collapsed. The subject's heart had then stopped.
Analysis: While slowing time down, the subject gains immense energy, with an accelerated heart rate, the effects of usage in deceleration of time have been confirmed to be completely lethal.
Test B - Date 12/22/2012
Subject: Attempt to accelerate time using SCP [####]
Procedure: Allow D-Class Personnel to utilize SCP [####] to accelerate time
Results: Subject is lethargic, ready to fall asleep, their heart rate slows to 54 BPM as if they had been resting for several hours. The subject's pupils are dilated and muscles are slightly torn.
Within 36 hours, the subject reverted into a younger stage in their life. This could be attributed to SCP-[####] possibly containing the ability to reverse aging.
Within 72 hours, the subject had completely been reduced to atoms. Testing is off-limits.
Analysis: Accelerating time seems to have completely opposite effects to that of slowing time with the exception of the slight tearing of muscles, however, the personnel had died in a more reversal-time, type of death, while in Test A, the subject had died of a time-progression overload type of death, the opposing effect of the entity.
