People with lower extremity amputation (LEA) have persistent problems with balance, falls, residual limb pain, functional mobility, cognitive attention during gait, and satisfaction with participation in daily activities, despite using prostheses. The purpose of this randomized clinical trial is to advance understanding of how dynamic foot design features may help people with LEA This study will include people with above-knee amputations, or with bilateral amputations, or with below-knee amputations and lower levels of mobility. The main study questions/goals are: 1a) To determine if frontal plane adaptation in a foot prosthesis impacts performance, comfort, activities of daily living, and community mobility in the study populations. To answer this question, we will compare a locked and unlocked version of the novel prosthesis. 1b) To determine how the unlocked investigational foot condition compares to the person's usual foot using the outcomes listed above. 2\) To examine the participants' lived experience during community activities. The study will use performance tests, questionnaires, logbooks, and interviews to monitor person-centered outcomes and perceptions of personal functioning during the use of the investigational foot (locked and unlocked) compared to the person's usual foot.