A guide block for stabilizing an edge of a glass panel relative to a surface is disclosed. The guide block includes a block base having a body of variable size and shape configured for mounting on the surface. The block base defines at least one fastening screw receiving hole on top and on a side thereof. The guide block further includes a mounting member having a pin extending therefrom an inner side of the mounting member. The block base has a front and a rear such that the front is configured to receive the pin in a hole therethrough such that the block base and the mounting member stabilize the edge of the glass panel disposed therebetween and the rear is configured as a receiving channel for stabilizing an edge of a sliding glass door disposed therein.