Popular Size: As a reason of Raspberry pi hat design: GPIO Pin connection (Expansion board) is about 11 mm high and the screw hole diameter is 2.75 mm, this spacer & screw & nuts pack is a perfect installation tool for Raspbery Pi 4 Model B, Raspberry Pi 3 model B+ / 3B / 2B /B+.
Packing List(124 Pcs/Lot): Add 4 x M2.5X12+6mm Spacer as user needs; 30 x M2.5 x 5mm Screws; 30 x M2.5 Nuts; 16 x M2.5x5 +5mm Spacers; 16 x M2.5x11mm Spacers; 16 x M2.5x11+6mm Spacers; 16 x M2.5x20+6mm Spacers.
Note: 1. Compatible with 2019 latest Raspberry Pi 4 Model B, Raspberry Pi 3 Model A+ / Raspberry Pi 3 Model B+ (B plus); 2. The above numbers behind M are for spacer/screw/nut tooth diameter x length, the unit is mm. Example: M2.5 x 5mm Screws.