VANSON 6mm Chrome Screw-In Tremolo Arm / Whammy Bar for import type guitars Black

VANSON 6mm threaded Chrome Tremolo Arm.

Arm DiameterM6(thread diameter in reality approx 5.80mm)

As a rule of thumb here’s a good sizing reference, duly credited to ‘CeltRocka’ on Strat-talk.com;
All USA strats: 10-32 UNF [equivalent 4.82mm]
All Made in Mexico and Made in Japan: M5 [4.80mm thread]
Squier Classic Vibe and Affinity- M5 [4.80mm thread]
Squier Bullets, Deluxes and Standards areusuallyM6 [5.80mm thread]but sometimes10-24UNC (M5)
Generic Imports Brands are often M6[5.80mm thread]

If you are unsure you can always try an M5 or M6 bolt from a hardware store first, to check the thread of your tremolo/vibrato unit.