This is about .1mm too large but I like to sand down the hinge pins for a snug fit.

Specs:

• Total 4mm x 4mm x 35mm (L x W x H)
• 4mm x 4mm x 2mm cap
• 3.2mm x 3.2mm x 33mm shaft

Specific model that this pin works for: https://www.printables.com/model/894405-lo