Effective solution for recapping blood drawing tubes, glass test tubes or plastic culture tubes Precision-molded, low-density polyethylene (LDPE) to maintain a tight seal during centrifugation, agitation and refrigeration procedures Color-coded for easy sample identification Tabbed design for easy cap removal Single-thumb tab design allows for the tubes to be placed closely in test tube racks. There are 1,000 white, 13-mm tube snap-cap closures in a bag. .