Brass bushings https://dailymail.com.ua/news/latunnye-vtulki-dolgovechnost-ustojchivost-k-iznosu-i-korrozii-dlya-nadezhnykh-soedinenij-v-razlichnykh-otraslyakh.html have proven themselves well in operation. Since brass does not rust or corrode, bushings made of this material are reliable and durable in operation. Bushings are inserted into the holes for the wire on the side bars of the frames. This is done so that the wire passes freely through the holes and does not cut into the wood. Stringing the wire through bushings is much more convenient than without them. The finished frame is of higher quality and smoother if you use bushings when stretching the wire.