PEUGEOT 508 Handbook page 156

Safety
Follow the instructions for fitting child seats contained in the seat manufacturer's installation guide.
the ISOFIX BABY P2C base must be installed in a way that the ISOFIX latches 3, 4 and 5 are visible; the support leg must have 6 holes visible.
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Baby P2C Mini and its ISOFIX base
(size categories: C, D, E)
Group 0+: from birth to 13 kg
Installed rearward facing using an ISOFIX base which is attached to the anchorage rings A.
the base has a support leg, adjustable for height, which sits on the vehicle's floor.
this seat can also be secured with a seat belt. In this case only the seat shell is used.
"Baby P2C Midi" and its ISOFIX base (size categories: D, C, A, B, B1)
Group 1: from 9 to 18 kg
Installed rearward facing using an ISOFIX base which is attached to the anchorage rings A.
the base has a support leg, adjustable for height, which sits on the vehicle's floor.
We recommend that you use the seat in the rearward facing position up to the age of 3 years.
this child seat can also be used forward facing.
this seat can not be secured with a seat belt.