Phoenix Contact 0824603 You can order a marker specifically designed for terminal blocks in various configurations. One option is to purchase a sheet of yellow markers with custom labeling according to your needs. The markers have a snap-in design that fits into a tall marker groove and are suitable for terminal block widths up to 8.2mm. Each sheet contains 56 individual labels, with text fields measuring 10.5mm in height and 7.6mm in width.