# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/(?=\b\d+[xX]\b)/\n/gm;t' <<< "Some description art.nr: 4457 72 1x ACOUCH 90X200 NICE GRAY (3 colli) 1x matras 85x205x12 2x matras 80x190x11 Some specs 14x Premium otherproduct 90x200x23 HR34"
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html