40cm Plastic School Teaching Triangle Rulers with Removable Handle. Introducing our 40cm Plastic School Teaching Triangle Rulers, specially designed for educators who work with both whiteboards and blackboards. These triangle rulers feature a removable handle for ease of use, allowing you to comfortably create precise angles and lines on various surfaces. Crafted from durable plastic, these rulers are built to withstand frequent use in classroom environments. Whether you're teaching geometry, drafting diagrams, or illustrating concepts, our Teaching Triangle Rulers are the ideal tools for bringing clarity and precision to your lessons, whether on whiteboards or blackboards.