The arms have a special holding vent position so you can receive fresh air without the hatch being all the way opened

IPS 1/2" Female Protrudes From Flange 3-3/16" (3-1/2" dpth) Flange Diameter 2-3/16" Turns On/Off 1-1/2 Mounting Screws 2 – No

while the same applies regarding its tensile and flexural strength

All-Round Light is mada of black plastic

two 1/2" threaded hose connections

Vetus P104373 - Chain Stopper 10mm Removable lever StSt VHF The arms have a specialChain stoppers hold the chain and take the load off the windlass. Always use a chain stopper to set and ride on the anchor,break free the anchor or to prevent accidental free fall of the anchor while under way.