12 x Number Plate Double Sided Foam Adhesive Fixing Pads Weatherproof Sticky Pads.

1mm x 25mm x 95mm long

These Are Manufactured Specifically For Number Plates, Super Strong & Durable with a Solvent acrylic adhesive

These HEAVY DUTY Sticky Pads and do what they should :) 

Ensure the mounting surface is flat if not select 6mm spacer pad which will absorb minor surface differences. If not I sell these also https://www.ebay.co.uk/itm/185423813705

Fitting Instructions 

The Number Plate Fixers - 1mm Adhesive Spacer Pads are for direct surface mounting on flat surface only. 
Ensure you clean all wax and dirt from mounting surface and reverse side of number plate  Apply pads to the reverse side of plate, Remove protective film from pads and press plate into position. Apply firm pressure for about ten seconds to ensure a good bond. Full bonding strength is reached after 24 hour and the minimum application temperature is 10c.

These pre-cut sticky pads add instant adhesion to any clean dry surface, and are WEATHER RESISTANT

They are the best available for a PERMANENT GRIP

Please see my other listings for more options.