Lunt Solar Systems ERF Energy Rejection Filter) sleeve for refractor SkyWatcher Evostar ED 80/600. Contains two parts: filter sleeve and cover. It must be screwed together with four 10 mm long M3 bolts with conical head. Inner diameter of filter sleeve is bigger than objective diameter to fill the gap with some soft material like black self adhesive velour.
ERF filter not included. Screws and nuts included.
Link for ERF filter:
https://tavcso.hu/en/product/LS75ERF
Link for telescope:
https://www.astroshop.eu/telescopes/skywatcher-apochromatic-refractor-ap-80-600-evostar-ed-ota/p,15056
Link for self adhesive velour:
https://www.astroshop.eu/straylight-and-glare-shields/astoptics-self-adhesive-velour-48x50cm/p,57841