16 or up -but keep in mind 16 is the highest strength you can get in nature anything else has been manipulated by man. If you are into strictly organic, go with 16 - if you don't care go higher.

Good luck! And yes go through OCF!!

Cheryl : Irritation - 2004 BX: 6/2008 : Inflam. BX: 12/10, DX: 12/10 : SCC - LS tongue well dif. T2N1M0. 2/11 hemigloss + recon. : PND - 40 nodes - 39 clear. 3/11 - 5/11 IMRT 33 + cis x2, PEG 3/28/11 - 5/19/11 3 head, 2 chest scans - clear(fingers crossed) HPV-, No smoke, drink, or drugs, Vegan