HCS Control Slides consist of formalin fixed, paraffin embedded tissue sections which contain known positive tissue elements. Use these slides with confidence to evaluate stain quality and performance in histology laboratories. StatLab HCS control slides are created using non-adhesion or adhesion white glass slides with 90 degree corners. Each package includes a specific staining protocol. Control slies are available in packs of 25 or 100 and contain one stained slide.