Hi,
Looking on Rimmers web site, there are 3 315mhz key fobs.
YWX101230A
YWX000310
YWX101230AP,
The last 2 are discontinued, the first one sells at £93.00 approx.
From this, you can check out the part numbers to see if they correspond with the Land Rover fobs.
Or, drop Rimmers an e mail for advice.
Cheers
David