Product information "Aluminum Standoff: 1/4" Length, 2-56 Thread, M-F (4-Pack)"
These hexagonal male-female aluminum standoffs keep parts spaced 0.25" (6 mm) apart and are great for building a multi-level robot chassis. Both ends of these 3/16"-wide standoffs have 2-56 threads. The standoffs are sold in packs of 4.
These M-F (male-female) aluminum standoffs are great for separating stacked components or chassis tiers. Each hexagonal standoff is 3/16″ wide with male threading extending 3/16″ to 1/4″ from one end (dimension M on the mechanical drawing to the right) and female threading to a depth of 3/16″ to 1/4″ in the other end (dimension F).
The standoffs can be screwed together to make longer standoffs.