Rectangular bututu wani nau'i ne na sashin murabba'i mara tushe haske bututun karfe mai bakin bakin ciki, wanda kuma aka sani da bayanan bayanan karfen sanyi.An yi shi da Q235 mai zafi mai jujjuyawa ko tsiri mai sanyi a matsayin karfen tushe, wanda aka tsara shi ta hanyar lankwasawa mai sanyi sannan kuma ana walda shi ta mita mai yawa.The kusurwa size da kuma gefen straightness na zafi birgima square tube tare da karin lokacin farin ciki bango isa ko ma wuce matakin juriya waldi sanyi kafa square tube ban da bango kauri thickening.