These fasteners are manufactured from 7075 T-6 Aircraft quality cold heading wire.
Fastener Dimensional Data for Metric Aluminum Button Head Cap Screws - Purple Aluminum: (Size: 4mm)

For Reference Only:

Metric Aluminum Button Head Cap Screws - Dimensional Data
Metric Machine Screw Threads - Dimensional Data

Find Coordinating nuts and washers for your Metric Aluminum Button Head Cap Screws below:

Nuts:

Purple Aluminum Locknuts