If you want something cheaper, let me know and I will source the appropriate fuse from Screwfix or Farnell, and stick a coloured label around it. I offer these at half of the price of the QSA ones — just let me know what colour label you want. For £1000 extra, I will print the arrow with a point at both ends so you can fit it either way around.
HiFi Tuning offer these 20mm fuses for inside your equipment, https://www.analogueseduction.net/fuses/hifi-tuning-supreme-3-copper-slow-5-x-20mm-t-audio-grade-fuses.html. From this site,
the caps as well as the melting wire consist of 99% pure silver and 1% of gold...
Specifications:
Straight melting wire consisting of Cardas Low Eddy Copper...
Julian F. G. W.
(Off now to oil my snakes...)