Background: At 2:01:34 on 05/13/20██ a suspected Dr. Wondertainment item was discovered outside Site ██. Agents were sent to retrieve it. The object appeared to be a mattress with various child-like designs and an attached document:

Wowee!! You're certainly lucky! You've just gotten yourself a Super Bouncy Mattress™, exclusively from Dr. Wondertainment ®. With this amazing product you can bounce sky-high, and don't worry about the ceiling! With this amazing product Dr. Wondertainment ® can bring you the best slumber party toy you'll ever find! Get your friends together and have a blast on the Super Bouncy Mattress™!!

When any human began jumping on the object, they would be propelled upward at heights in defiance of physical laws, and would not be injured upon impact with the object. An unidentified force prevented subjects from being propelled outside the space of the mattress, causing subjects to always fall back on to the mattress. Subjects would phase through any objects while being propelled, except each other. The object was classified as Safe and placed in containment locker 1563-F
On 06/05/20██ Site Director Timanson received this letter in his inbox:

Dear Dr. Wondertainment ® customer,
We hope you're enjoying all of our amazing products! Unfortunately, it has come to our attention that one of our items, the Super Bouncy Mattress™, has a defect. We ask that you return your edition of the Super Bouncy Mattress™ to Dr. Wondertainment headquarters at [REDACTED]. We will repair the defect and return it to you as soon as possible.
Thank you for your time,
Dr. Wondertainment ®

Site Director Timanson opted to not return the object. Investigation of the object showed no signs of defect. Agents were sent to investigate the area described by the document. For full information on the results of the investigation see document W-17.
On 06/21/20██ Site Director Timanson received this letter in his inbox:

Dear Dr. Wondertainment ® customer,
We hope you're enjoying all of our amazing products! Unfortunately, it has come to our attention that one of our items, the Super Bouncy Mattress™, has a defect. We ask that you return your edition of the Super Bouncy Mattress™ to Dr. Wondertainment headquarters at [REDACTED]. We will repair the defect and return it to you as soon as possible.
Thank you for your time,
Dr. Wondertainment ®

Site Director Timanson opted once again to not return the object. Regular testing continued, as well as several unusual tests in order to detect the supposed defect.
On 07/02/20██ Site Director Timanson received this letter in his inbox:

Dear Mr. Timanson,
Records indicate that you have yet to return your Super Bouncy Mattress™. It is extremely important that you return it at once! Be reassured you will get a new Super Bouncy Mattress™ back! Your haste in this is appreciated, as cooperation from every party is necessary in order to keep things safe and fun for everyone!
Sincerely,
Dr. Wondertainment ®

After consulting with the O5 counsel, Site Director Timanson concluded that it would be in violation of Foundation policy to surrender an anomalous object. Testing of the object has continued.
On 07/10/20██ Site Director Timanson received this letter in his inbox. Unlike the previous letters, this document had been hand written:

Dear Mr. Timanson,
We at Wondertainment have asked you time and time again to return your mattress. Once again we request that you please return it. You are the only person that has failed to do so, and as such we conclude that you obviously have no cause to do so. Since you refuse to return the mattress, this is a disclaimer stating that Wondertainment claims no responsibility over any damage to property, injury, or loss of life caused by the defect that you have been repeatedly warned about. You have brought this upon yourself.
Sincerely,
Dr. Wondertainment

Director Timanson refused to return the object.
Incident Report ████-F:
SCP involved: SCP-████
Personnel involved: 163 personnel involved, for full list see Document ████-E
Date: 07/17/20██
Location: Site-██
Description:
During routine testing of SCP-████, a spring broke free of the object. Due to its anomalous properties, the spring proceeded to bounce off of the ground beneath the site, constantly accelerating. The spring was able to pass through walls, ceilings, and other obstructing objects, but presumably due to its design instead accelerated through humans, typically shredding a 25 centimeter hole through several major organs due to its vertical orientation. Its state of constant acceleration caused it to bounce throughout Site-██ several times. The spring was finally arrested when it came into contact with SCP-████.
Addendum: Casualties numbered 155 (approximately half the site staffing), with 62 personnel permanently injured and 93 personnel dead. SCP-████ has been reclassified as Euclid and placed in a specialized containment locker at Site-██. Protocol Wonder-Alpha was put in place in order to deal with future recall of Dr. Wondertainment products.