There is transparent strings for various types of knot tying practices.
Also, with the hole on the bent side of the board, you can practice deep hole knot tying.
With two colored string, you can practice the knot tying much easily and judge your knot tying clearly.

ModelS-KTC-01Skills1. Various Knot tying skills2. Deep hole knot tyingFeatures1. Half dyed enlarged suture2. Transparent cylinder3. Repeatable useSpec+Two Colored String x 1ea- 720mm / 7.5gHolding Board x 1ea- 220mm*65mm*80mm / 144.5g