“NdFeB” is short-hand for Neodymium Iron Boron magnet material. Good descriptions of this type of magnet material are available at:

Sintered:

• https://www.arnoldmagnetics.com/products/neodymium-iron-boron-magnets/
• https://www.kjmagnetics.com/neomaginfo.asp
• http://www.magnetsales.com/Neo/Neo1.htm
• http://en.wikipedia.org/wiki/NdFeB

Bonded:

• http://www.permanentmagnet.com/neodymium_bonded.html
• https://www.sintex.com/en/magnetic-technologies/technical-data/item/stx-polymer-bonded-ndfeb
• https://www.magdev.co.uk/media/wysiwyg/Bonded_NdFeB_Table.pdf
• http://www.magnetapplications.com/products/magnet-assemblies/neoblend-isotropic-ndfeb/
• https://www.buntingeurope.com/wp-content/uploads/2018/07/Bremag_Bonded_NdFeB_DataSheet_Iss1.pdf
• http://www.arnoldmagnetics.com/wp-content/uploads/2017/10/Arnold-BMG-Magnet-Material-Specification-Brochure.pdf