slope Fatal Squire 4mm cross section o ring a little plus kill
OR58X4 FKM FPM Rubber O Ring 58mm ID x 4mm Cross Section | eBay
YINGJUN CS2.4mm FKM Rubber O RING OD 39/40/41/42/43/44/45/46/47/48x2.4mm ORing Fluorine Gasket Oil seal Green 50pcs O-Ring Ring Gasket (Size : OD39x2.4mm) : Amazon.co.uk: Business, Industry & Science