Filter products in stock and out of stock

Тут https://baza.cn.ua/admin/shop/products/?filtercustomkodkategoriirozetka23=&filteremptyfieldid=&filtercustomtekst2=&filtercustomrozetka17=1&filtercustomspivrobitnik21=&fromfiltercustomzristchislo15=&tofiltercustomzristchislo15=&filtercustom562=&filtercustom531=&filtercustom583=%D1%88%D0%BE%D1%80 %D1%82&filtercustom564=&filtername=&filterarticul=&filterid=&filterpricefrom=&filterpriceto=&fromfiltercustomzalishok25=&tofiltercustomzalishok25=&filtercdatefrom=&filtercdateto=&filter_show_avail=1&filter_show_not_avail=1&filtermodel=&filtershare=5&categoryid=19 There are two filters http://prntscr.com/u6roln But somehow it's not logical when I choose both of them It turns out that in order for me to see all the products now, I need to either uncheck the "Product in the presence" checkbox or tick 2 checkboxes It would be more logical to make not 2 checkboxes, but a drop-down list in