Magnet holding strengths are personal. All our magnets styles will hold a fully loaded rack up to 7/8” thick glass, but due to the frag locking mechanism the rack may move when removing plugs depending on the combination of frag locking strength and frag plug you choose.
Due to the modular design of the Hive frag racks you can quickly change the magnets to increase or decrease the grip that the rack as on your aquarium glass. Kits are sold in sets of two and include everything necessary to upgrade from the base model. Inner and outer magnets do not need to match and changing one side is a good way to incrementally increase the strength without going too far.