I am a leisure / fitness runners with 2-3 Läufchen per week, about 60-70 Km / month. Also like to ride long mountain bike tours and am a regular at the gym. After lasting negative experience with POLAR (battery replacement expensive and cumbersome; POLAR clock treated with kid gloves and yet 2 x total failure ...) I decided to use a rock-solid, cost-effective and high-quality heart rate monitor. As I hit the jackpot with my 14 months ago numehr Sigma 25.10. Easy to operate, after a year a self-made battery change (never a problem with existing key in the delivery), required values shows the clock well and accurately to ... what more could you want. The menu system is foolproof and the processing of Ührchens is top. The display is clear and the settings of the personal values and target zones is super easy. I carry the 100% waterproof clock now also like in everyday life, office, etc. because it weighs just nothing and is so comfortable to wear. With the supplied rubber base that can be fixed to the handlebars, the clock is also my constant companion on my bike rides. I lass'die clock also while swimming and showering in, water is not an issue. Also the chest strap that came with is top. Betteriewechsel also easy Tragekomforrt high. Before creating the contact surfaces wet a little with water and off you go. A little schde that you can save only the last training or alternatively, the total training values looks summed since the last RESET. But that's more of a Luxuxproblem. Conclusion: Anyone on a budget a thoroughly honest and solid, highly reliable heart rate monitor takes him time, calories burned, heart rate and training zones indicating this is the place to 100%. No more and no less. I have now bought another 2 Sigma heart rate monitor for my son, he is also topzufrieden. Unrestricted buy recommendation, top product!