The performance of approx. 115 Shield supports employed in 2 panels at Kaiser Steel's Sunnyside No. 1 Mine is described. These Hemscheidt 320 hsl caliper-type shields were installed originally at Kaiser Steel's York Canyon Mine as a demonstration program and later were transferred to Sunnyside. This report describes the rehabilitation of the shields prior to their installation at the second mine and the mining experience using these supports. The findings show that, in general, the shield supports were able to perform adequately in the wide range of seam heights (from about 6 ft to about 10 ft) within each panel. Some problems were experienced with roof stability immediately ahead of the supports (the only strata control problem experienced with these units); this may be attributable to the movement of the roof canopy away from the face, an inherent feature of caliper units. Overall, the supports functioned well. During the trials, a 24-hour production record was set with 20,384 tons mined. Throughout the mining of both panels, high production and productivity were maintained. Although mining conditions are not directly comparable between these panels and an adjacent panel that was mined with chock supports, the peak productivity was between 20 and 55 pct higher in the panels where shields were employed.