The old one for pre 2007 model was velcro attachment at the sides. It just didn’t “velcro” to the carpet and would drop off. There was also a fricton fit to the rear of the seats that didn’t have much friction so again would drop out.
The lastest one seemed to have cured the problem with proper hook attachement to the side luggage system and straps over the head rests. Two problems. The hooks are too loose, particularly on one side so drop out quite easily. The headrest straps must be for the Volvo truck (not seat or headrest) as the straps are way too wide so it pulls the liner in at the seat backs like cheap shopping bags
2 dogs / 5miles and all hell has broken loose with the boot liner even with a dog matt to hold the base in place.