1922 7500 rub. blue, horizontal watermark, gutter tete-beche block of four with sheet margin. These stamps were printed in large gutter panes and cut along the gutters by the postmasters. They were not sold in philatelic shops and only six tete-beche pairs survive. This is believed to be the only known gutter tete-beche block of four. A fabulous rarity from RSFSR, ex-Shtern (realized $149,500)