Research aims: The aim of the research is to identify the effect of the Hydro Hip on improving: Arms movements (50 m arms pulls number- 50 m arms movement timing- 50 m full cycles timing- Evaluate the arms movements' performance)  Digital level of 50 m breaststroke. Research Methods: The researchers used the experimental method, by using the experimental design of two groups; control and experimental by applying the pre and post measurements of both groups. Research Sample: The total sample number of the study consisted of (36) juniors from those who have learned breaststroke and can perform arms and legs movements. A breaststroke performance test was done and (20) swimmers who performed the arms movement efficiently were excluded, so the sample became (36) swimmers with arms movements flaws and perform the legs movements efficiently. The sample was divided as follows; (12) swimmers for the pilot study, and (24) swimmers divided into (12) experimental group and (12) control group. The two groups underwent training to improve arms movement in breaststroke. The experimental group was trained with the Hydro Hip tool, and the control group underwent the same training without the tool. Conclusion: Training using the Hydro Hip tool led to improvement of the skill variables. There are differences in the change rate between the post measurements of the experimental and control groups in the skill variables in favor of the experimental group.