Snipe,
That's real human gray since it's a stock unit. You can get synthetic on a stock unit if you specify it. Whether you want synthetic or human gray is a personal choice. Synthetic gray does not accept dye. Of course the synthetic hair does not have the same characteristics of human hair (light reflection, etc.) put mixed in with real human hair in percentages under 35% these are virtually undetectable. The body wave will be no problem. Are you going with 55% gray on top? Usually it's the temple areas that have the highest percentage of gray. Can you post a photo of the look you'd like to achieve? Then I'll be better able to advise you on gray percentages. Thanks.
Regards,
John