Watch List notes:

Islamic Coins, Abbasid, Harun al-Rashid, dirham, San'a' 183h, rev. field: alif fa, kaf or mim alif/-/Yazid, wt. 1.11gms. (Lowick 546 for date), chipped, clipped, otherwise fine, very rare
This and the following dirhams from the mint of San'a' are all of the highest rarity. Judging by their frail fabric it is no surprise that so few have survived and that they are so rarely encountered. (400 - 500 GBP)