Secchi Disc with Holding String Subcategory_Stopcocks and a bar magnet for

and a bar magnet for both electrostatic and circuit investigations

Regulated dual-output power supply showing independent LED readouts of voltage and current

supplying the plastic-coated counterpart to bare copper for circuit wiring where exposed conductor must be avoided

engineered for low-friction operation during accurate mechanical-advantage measurements

drop-tube sterilization

Secchi Disc with Holding String Subcategory_Stopcocks and a bar magnet forLowers into ponds, lakes, or streams on its holding string until the alternating black and white quadrant pattern disappears, giving a direct field reading of water clarity.