You simply turn them upside down and watch the two differently coloured bubbles simultaneously walk down the staircase to the bottom of the tube. The liquid timer takes approx. 1 min to run through. H11cm x Dia. 5cm
You simply turn them upside down and watch the two differently coloured bubbles simultaneously walk down the staircase to the bottom of the tube. The liquid timer takes approx. 1 min to run through. H11cm x Dia. 5cm
