No need to waste money on the expensive ones the JBL on amazon are good and cheap

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https://www.amazon.com/JBL-Hydro-Spearfishing-Freediving-Plugs/dp/B0054MXWH2/ref=sr_1_1_sspa?keywords=JBL+Hydro+Seals+Aqua+Plugs&qid=1562529194&s=sporting-goods&sr=1-1-spons&psc=1&smid=A138GYT3Y3DZXX