M4 Threads. Bolts have 6mm of thread.
100 x Meccano Part #37 Brass Cheesehead Bolts And Square Nuts Part 37b 37a
100 x Meccano Part #37 Zinc Cheesehead Bolts And Square Nuts Part 37b 37a
100 Meccano Slotted Cheese Head Bolts And Hex Nuts Part 37b 37c Zinc
100 X Meccano Dome Head Bolts And Hex Nuts Part 37b 37a Brass Plated
Meccano 50mm Long Slotted Cheesehead Brass Bolts x 10 (111g)
Meccano 25mm Long Slotted Cheesehead Brass Bolts x 10 (111h)
