VOOXA Premium Window Sill Screws 3.9 x 22 mm TX15 Stainless Steel A2 with Polyamide Disc and Cover Caps Anthracite RAL7016, for Aluminium and Plastic Window Frame, Pack of 50 : Amazon.co.uk:
Fischer 60275 Cover Cap ADF 12W White For F-S Window Frame Fixings Pack x 100 from Lawson HIS