The Sirka is a great invention! You can allot different counts to three different colored hands on the counter and I love using it.
The Sirka® counter is available in two beautiful colourways - yellow and blue (birdie) and pink and purple and turquoise (dolphin). There is also a rainbow colourway which is for two counters. The counter, which tends to your knitting by tracking three separate counts, AT THE SAME TIME. You don't even have to remember when to stop counting; the Sirka® counter does it for you.
Here's how: The discs underneath the "face" of the counter rotate, allowing you to align the disc handles, or "crowns," with numbers on the face. Balls and springs hold the crowns in place until you decide to advance your counts. The "hands," which fit into slots on the face, remind you where each count ends. Revolutionary! The ability to have several counts is very useful when, for example, you have a pattern over a number of rows (e.g. pattern over 16 rows) and need to repeat it several times (e.g. 10).
The counter means that you no longer get lost. You will receive a counter with instruction manual, but tutorials are also available at https://www.grellowgray.com/Grellow_Tutorials.php. To keep your counter safe, you may want to consider purchasing a Bento Box in the same or contrasting colourway at http://www.theyarncafe.com/bento-box-for-sirka-counter/.
Note: If you choose the rainbow colour, you are purchasing two counters.
Too versatile to be considered a row counter and invaluable when keeping track of pattern repeats when shaping. Highly recommended.
I haven't used this with a project as yet but I have played around with it and believe that it will be extremely useful if not invaluable.