I've read some posts about button magnets and am curious if you guys that use them use the soft flexible style of magnets common found on refrigerator magnets OR if you use real rare earth magnets?
I've never tried the soft flexible style but I did jam a cow magnet down a pipe I set years ago and it made it sing.
For the small disks set in a 5/16ths hole I use rare earth magnets. For larger monuments I use the plastic covered color code magnets used by BLM.
Cheap magnets deteriorate.
thebionicman, post: 438214, member: 8136 wrote: For larger monuments I use the plastic covered color code magnets used by BLM. Cheap magnets deteriorate.
#BLM (battery life matters)
I have used ceramic magnets. Ebay.
I have no idea if they deteriorate.
The flexible ones often have alternating polarity strips so don't project a magnetic field well at any distance.
I recently found a destroyed bench mark that had disk magnets at the bottom of the 30" aluminum pipe. It didn't give much response on the locator. Still wondering why they weren't near the top.
Bill93, post: 438261, member: 87 wrote: Still wondering why they weren't near the top.
I believe the theory is that if an equipment blade were to shear off the top of the monument, the magnets at the bottom would remain to facilitate recovery of the monument location.
That could be a good idea for cadastral or other horizontal monuments, but of course of no help if an elevation mark gets disturbed. It didn't help in this case.
From thread: https://surveyorconnect.com/community/threads/destroyed-bench-mark.331227 
USFS would require that magnets be placed in all alum. pipe monuments. They were the black Ferrite type, about half the length of a C size battery.