Very practical, I recommend

Product that I knew and therefore ended up buying because it was necessary. Good product with a very good quality/price ratio.

article on, used in many harmonies, for my personal experience. Very practical to use, easy to put in your pocket, faithful friend of the musician. I use it every day. Recommended for all musicians like me, amateurs. It sometimes allows surprises compared to what one thought was right. For me, trombonist, it is very precious and useful.