Hard Hat Suspension, Head Protection Suspension Type Ratchet (4-Point), Fits Hat Size One Size Fits Most, For Use With Thermalgard (R), Topgard (R), Compatible Hard Hat/Helmet Brand Name MSA SAFETY, Compatible Hard Hat/Helmet Grainger Part Number 3RRR5, 3RRR6, 3RRR7, 3RRR9, 43FD16, 475385, 4LP01, 4MC41, 4MC61, 4MC62, 4MC63, 4MC64, 4MC65, 4MC66, 4MC67, 4MD34, 4MD36, 4MD37, 4MD38, 4MD39, 4MD40, 4RB37