I say, and with God's success: It suffices if they are two separated fingers; because the space between them is the size of another finger, thus wiping with them is like wiping with three fingers, which is the amount that must be wiped. Refer to: Al-Muhit, page 340, and Ghinayat Al-Mustamli, page 110, and Sharh Al-Wiqayah, page 114, and God knows best.