35 pieces in 5 different sizes: 2x8cm (10pcs), 3x7cm(10pcs), 4x6cm (6pcs), 5x7cm (7pcs), 7x9cm (2pcs), all the boards are thick and double sided. Durability: High quality of durable glass fiber -FR4 material with 1.6mm thickness makes a very solid and sturdy prototype circuit board. Easy installation: 4 mounting holes at the corners of the boards make it very convenient to solder components and install them together. Easy to use: Pre-tinned plated holes on the board make it very handy to solder components and sensors for your projects. Meet your different demands: fit for large, medium and small electronic experiments and DIY projects.