Fits well. Extra lid is provided. It even has room to fold and leave open the bit of the lower lid for the cable box just inside the trunk.
It provides useful space in the boot for cables, high vis jackets & so fort.
Time will tell how well it wears.
The seller appears to be some kind of camera shop that's an alter ego for ultramax uk website (same address).
The batteries from there are a bit cheaper than here, and come with a mains charger.
One of the big supposed plusses of LiFePo4 is that they have more charge cycles than SLA. Since it will take several years to reach that (all being well) I cannot comment in any useful time-frame for anyone.
What I can say is that they seem to produce the juice OK. I use these to power the avionics in a glider, and after 3-4 hrs flight with a draw of around 0.5A, the voltage still shows at 13.1. Furthermore, when I press transmit on the radio, which normally draws another 2.1A, the voltage stays at 13.0.
I have a slight concern that there is a slight spark when I connect the charger, after the batteries have been used, and before turning on the charger at the mains, but there seems to be no issue.
They're lighter than SLA, of course. Other pilots have been complimentary about their Ultramax SLA batteries, so I'm optimistic that the quality will be good on these.
BTW: The photo shown here does not reflect what I got. Mine have the normal spade terminals, and a white label on the side. Also measurements are 95.5mm (excluding terminals) x 150.5 x 64.2 (checked using vernier calipers)