These needles are the right duration, and will not puncture the liners if thoroughly used WARNING: Merchandise can't be returned or exchanged if liner is weakened or punctured because of improper inflation or needle use A flexible liner suitable for various head shapes offers comfort and steadiness Removable dampness-resistant liner https://paxtonepklg.blogsvila.com/30928144/what-does-speedflex-adult-large-mean