ScentBlocker Scent Protection Factor (SPF) Rating System gives you a scent elimination guideline to help you design the best scent control system for the way you hunt. The higher the rating you can combine, utilizing all key areas outlined, the more effectively you will be able to hunt. We recommend at least a combined minimum SPF factor of 100 to be successful and see positive results. The more areas you can utilize in your scent control system combating odor at different levels, the more positive results you will experience while hunting. ScentBlocker? SPF rating of 40. Soft leather palm treatment. Color: Realtree? AP HD?.