I think the Bare Minerals compact is SPF 20. For extra SPF, I use a gel sunblock under my mineral make up or powder make up instead of a primer. I prefer a gel formula because they don't make me as greasy as traditional sunblock, but they can cost more. I've been using SolBar's in SPF 30 but I got a sample of CoTZ's Face Natural Skin Tone Sunblock in SPF 40 from Ulta and I think I might be in love
. It feels more like a primer than a sunblock and it takes make up SO WELL. Nothing budged once I layered over it.