A Magnaprobe™ can be one of the most useful tools in science lab magnetic field experiments. Be sure you're buying a genuine UK made Cochranes of Oxford Magnaprobe&trade. We can't name names but world renowned National Labs buy this tool from us to test the magnet fields around their particle accelerators & other equipment.
Unfortunately you can't go on price alone. Some are sold at half our price & we've even seen them listed at triple the price. So, how you tell if you bought the real thing? We stand behind the real thing, see more below.
One of the obvious differences is in the magnet mount. The handle/frame of the fake Magnaprobe™ typically weighs 15 % less (4.6 g vs 5.4 g) than the real thing. The pivots are poorly moulded (see photo) which makes the device less sensitive / accurate as well as less durable.
The Magnaprobe™ magnet's bearings are not centred which can cause one end to sometimes catch on the plastic frame as it turns. This causes it to plot the magnetic field inaccurately - due to its being weighted more to one end.
The AlNiCo magnet in the fake is shorter. The one we tested was 4mm less, 117 vs 121 mm and ~5% thinner, 3.0 vs 3.15 mm. The grade (quality) of the AlNiCo magnet is less according to test. All these makes the fake quite a bit less sensitive/responsive.