car seat inserts

I need to replace the insert for my car seat. I know they say do not purchase them and only use the ones that come with the car seat. Is it ok to buy the insert from the manufacturer? For example I have a chicco keyfit30 so is it safe for me to buy this insert since it is made by the same company? 
http://www.chiccoshop.com/parts/car-seats/cubes---keyfit-or-keyfit-30-head-and-body-insert/12071015045.html?zmam=69233264&zmas=1&zmac=1&zmap=12071015045&gclid=Cj0KEQjwkdHABRCHiZ2gs6yGh50BEiQAA91WlqwDm0YgMVQa92TDie7-HYmroFZntrjgIbNM3XJGUS8aAuEJ8P8HAQ