Brady Authentic M21-187-C-342 PermaSleeve Heat Shrink Tubing – Black on White, 0.335" W x 7' L, 3:1 Shrink

Overview

Meet Brady's M21-187-C-342 PermaSleeve heat shrink tubing, a non-adhesive, printable sleeve designed to wrap around wires and cables for insulation and enduring identification. When paired with Brady printers, it delivers fast, crisp text that remains legible in tough environments.

This full-circle sleeve is a 3:1 shrink, so you can shrink it evenly around a wire bundle for a clean, permanent look. The material is irradiated polyolefin, built to resist the temperature swings and physical wear common in electrical work.

Why it matters in the field

• Durable insulation that protects against heat and abrasion while keeping wiring easy to read.
• Black text printed on a white sleeve offers high contrast and legibility.

For environments where chemicals, grease, or cleaners are part of the workflow, Brady PermaSleeve shows resistance and stability. It is UL recognized and RoHS compliant, and it is compatible with BMP21-PLUS, BMP21-LAB, IDPAL and LABPAL printers, enabling on-site labeling with Brady quality.

Printing and compatibility

The B-342 sleeve supports both thermal transfer and dot matrix printing. Brady ribbons R6600, R4300, R4502S, R6000, R6700, and R5000 series are recommended for various ink effects and reliability. Print on white sleeves with black text for durable identification that remains legible even after exposure to grime or oil.

• Color and fade resistance keep labels legible longer.
• Fast shrink with a standard heat gun.

Sizing and fit are important: the B-342 line includes several inner diameters and gauges to accommodate a wide range of wire sizes. Use the Brady sizing chart to select the right sleeve for your cables, and shrink with a conventional heat gun to achieve a secure, full-circle wrap.

Use cases and benefits

Electrical panels, wire harnesses, and control systems in manufacturing floors, data centers, and service vehicles benefit from PermaSleeve's combination of quick application and lasting readability. While results depend on printing setup and environment, users report clear labeling that survives routine maintenance and occasional exposure to cleaning agents.