A genuine Blackmagic replacement thumbscrew for the URSA Viewfinder, in the 1/4in-20 thread. The viewfinder tightens onto its mounting point by hand, and this is the screw that does it — no tools needed, quick to fit and quick to release when the camera breaks down for transport.

Small parts are the first thing lost on a working set, and a missing thumbscrew grounds an otherwise perfectly good viewfinder, so it's worth keeping a spare in the kit. Blackmagic also produces a 3/8in version of this screw — check which thread your mounting point takes before ordering.

Key features

• Genuine Blackmagic spare part for the URSA Viewfinder
• 1/4in-20 thread
• Tool-free — tightens and releases by hand
• Matching 3/8in version available for the larger mounting thread