Excellent color filters, at an affordable price! It's easy to illustrate color mixing by subtraction. Simply overlap two colored paddles and place them on an overhead projector. A brilliant display of complementary colors will appear-yellow and blue form green, yellow and red produce orange, red and violet make magenta, etc. Is it possible to form red, yellow or blue? Students will easily see the distinction between primary and complementary colors. Set includes six transparent paddles colored red, orange, yellow, green, blue and violet.