Abstract: A spacer unit, a discharging gun and a method of retaining a spacing to avoid loss of elastomeric seal between two surfaces are described. The system is particularly useful in the glazing trade for sealing large plate glass panes into aluminum frames. Each unit comprises a plurality of blocks skeletally inter-connected by webs. The cross-sectional area of the blocks and webs presented to a compressive force is still small relative to the cross-sectional area lying within the outer periphery of the unit.