Parking cisbo sensor - do I need spacers ?

[Hobbes]

hi all,

i have fitted a set of these sensors that i bought from eBay. They work "ok" but i am getting some erroneous beeping which may be from the ground. i have seen in other posts that some have had spacers in their pack (some not!) but ther

e were none in mine. They were sold as cisbo but box when it arrived was unbranded. i am pretty sure they are cisbo as everything is identical to the packs in their website.

Does anyone know where i can get spacers or alternatively have some spares that they don't need?

alternatively, If I am expecting too,much from these and they do chuck out the odd beep or two, then let me know.