Per 
Item #: SCP-XXXX
Object Class: Safe/Euclid/Keter (indicate which class)
Special Containment Procedures: SCP-XXXX is to be contained in a 10x10x10 meter containment chamber with a Sodium-24 sample placed next to it. SCP-XXXX is to remain on a electronic scale along with another Geiger Counter no more than 1 meter away from SCP-XXXX also placed on a electronic scale.
Both items weights are to be monitored in order to note when a switch occurs.
The Sodium-24 sample is to be replaced 2 hours before its half life is reached. New Sodium-24 samples are to be inspected before replacement in order to insure no significant decay has occurred before being used. Samples are to weigh no less than 15 grams and are to be handled with necessary radiation shielding when interacted with.
If SCP-XXXX is not observed to switch with the other Geiger Counter, increasing its range beyond the containment area. Site Personal will be instructed to not be in possession of Geiger counters or handling of radioactive material while within SCP-XXXX's range until it begins to once again reduce back to it's minimum range. Radioactive material use is strictly prohibited within SCP-XXXX consideration range.
Description: SCP-XXXX is a CD V-700 Geiger counter in great disuse weighing 1.2Kg without batteries. The bottom of SCP-XXXX is currently covered in rust, its meter face is cracked in several places, and has a dent with a radius of 5cm and depth of 1cm on its frontmost side.
Once every 24 hours SCP-XXXX will attempt to switch places with another Geiger Counter in range with a 84.2% success rate. This range is determined by the Half Life of the closest radioactive material near it. 0.02 seconds after this switch SCP-XXXX and the Geiger Counter that it exchanged spots with will appear to be the other via anything less than an rigorous inspection for up to 2 hours. However both counters will maintain their physical characteristics such as weight, buoyancy, and density.
The radioactive material that SCP-XXXX bases its switch distance on is the radioactive material with the highest half life within a minimum range of a 4.88 meters. The area of this effect has been determined to be a half sphere with its bottom being aligned with SCP-XXXX's bottom most face. If SCP-XXXX is unable to switch places with a Geiger Counter within its Half Life range its range will increase by 0.305 meters for each successive failure. Reducing by the noted amount each time it successively switches after a first successive switch.
If SCP-XXXX is used to measure radiation levels it has a 74.6% success rate of providing a correct measurement, a 15.2% chance of providing a measurement between +- 5% of the correct measurement, 9.8% chance of a measurement +- 75% of the correct measurement, and 0.4% chance of a measurement +- 200% of the correct measurement. If SCP-XXXX provides an incorrect measurement a user of SCP-XXXX will believe that SCP-XXXX measurement is entirely factual. Users will also not be effected by the actual radiation levels of the measured object but rather the incorrect measurement provided by SCP-XXXX. This anomalous effect wears off after 72 hours of being applied or if dissenting evidence of SCP-XXXX's measurement is shown to the user.
SCP-XXXX has also been noted to be able to teleport in response to perceived danger distances corresponding to its Half Life distance.
Addendum: [Optional additional paragraphs]
Equation for Distance Corresponding to Half Life in meters
D(s) =1.67+log_5.21(λ)
