it for outside birdcages that dont have the ablity to hang birdswings so i created my own. it screws on with a 3.5mm x 20 woodsrew with a head of 7mm.
screws u can find here https://www.conrad.be/nl/p/fischer-653931-verzinkkopschroeven-3-5-mm-20-mm-kruiskop-pozidriv-galvanisch-verzinkt-50-stuk-s-1878377.html?t=1&utm_source=google&utm_medium=surfaces&utm_term=1878377&utm_content=free-google-shopping-clicks&utm_campaign=shopping-feed&vat=true&gclid=Cj0KCQjw4PKTBhD8ARIsAHChzRKl5LmQ-n5yQnrzRcMoBwdcvCnJZXthnVcS07F_wsckO6qcFk9nOjQaAnISEALw_wcB&tid=16860426636_pla-1878377&WT.srch=1
or here
https://www.amazon.nl/fischer-Power-Fast-FPF-spaanplaatschroeven-houtmaterialen/dp/B0126R0ROS/ref=sr_1_1?__mk_nl_NL=%C3%85M%C3%85%C5%BD%C3%95%C3%91&crid=2AHG1O8SBP28O&keywords=fischer+sz+3.5x20&qid=1652354150&sprefix=fischer+sz+3.5x20%2Caps%2C62&sr=8-1
The author marked this model as their own original creation.