4 glass lenses, one pair plus, one pair minus, with either ± 0.25 or ±4.00DS diopters in 0.25 increments.Test and train for accommodative facility, accommodative rock, positive/negative relative accommodation and convergence and fusional convergence reserves. May delay bifocal use with some early presbyopes. Assists in hyperopia screening and lens demonstrations. Durable, white plastic holds shape under low heat for lens insertion. Powers listed on handle.