<html><head></head><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px"><div id="yui_3_16_0_ym19_1_1473379831696_2913">I have been reading the Mantis submersible spec sheet, and the aft entry dome is also the Op valve. The dome is spring loaded to allow it to open a wee bit in the event of an OP. Cool!</div><div id="yui_3_16_0_ym19_1_1473379831696_2913">Hank</div></div></body></html>