When you race HARD, and you rip through as many hoists and douses as we do sailing W-L legs all the time, you should expect to start wearing through the sideplates of your halyard exit block right? Wrong! Thanks to Harken Protexit blocks, wear from side angle loading is not inevitable. Protexit 's all-aluminum, wear-resistant housing carefully ushers line in and out no matter the angle. There 's more: Protexit blocks offer higher working loads than any small boat exit blocks we 've ever made. Protexit aluminum sheaves rotate on sleeve bearings with Delrin ® sideload balls so they don 't deform in extreme conditions, while reducing wear on the halyard, too. Delrin is a registered trademark of E. I. du Pont de Nemours and Company or its affiliates.