Hakkin mallaka © Zhengzhou Huitong bututun kayan aiki Co., LTD
An kafa bututun ƙarfe mara ƙarfe (smls) ta hanyar zana madaidaicin ƙwallan sanda don ƙirƙirar ƙwayar sananniyar ruwa, ba tare da walwala ba ko kashin. Ya dace da tanƙwara da flow. Mafi fa'ida yana kara karfin girman matsin lamba. Don haka ana amfani dashi sosai don tukunyar jirgi da jirgin ruwa mai matsin lamba, yankin da yake da shi, mai da kyau, da abubuwan kayan aiki.
S31803 shine tsarin ƙididdigar lamba (mara izini) ƙira don asalin Duplex bakin karfe. Kungiyoyi masu ciniki da yawa sun kirkiro da kungiyoyin kasuwanci da yawa a cikin shekarun 1970 don rage rikicewa yayin da aka kira kowa abubuwa daban-daban, da kuma mataimakinsu. Kowane ƙarfe yana wakilta ta hanyar wasiƙu da lambobi biyar, inda harafin yake wakiltar jerin baƙin ƙarfe, I.e. S for bakin karfe.