text: Adrian if you buy second hand check the serial numbers which do rub of easily.you may have warranty left too.The serial stickers tell you if its been opened if they are damaged.
  The gadget works ok but I do not like the tone. A bit on the low side for me that is very noticeable on the SST and gold Bug Pro and especially on the SST because it has tone ID that does not cover a very high range. So a lot of targets sound a low-ish tone through the Pro Sonic. The Gold Bug is not so bad although the tones are mellowed a bit.
  I can notice a slight delay in audio response from when the coil passes across a target to when the tone is heard in the HPs or spkr. However the response is very much better/ faster than with other wireless units that I have used.
  Works perfectly with the Safari. Is OK with the Infinium but tone is a bit scratchy with this tecta. Works well with the Sov XS and is fine with my home built PI,