Coolant bottle fittings?

I've used polypropylene bulkhead fittings in the past on overflow bottles. Something like these on ebay.

https://ebay.us/m/fra48S

I've used polypropylene bulkhead fittings in the past on overflow bottles. Something like these on ebay.

https://ebay.us/m/fra48S

https://www.amazon.com/Metaland-Stainless-Bulkhead-Thru-Bulk-Straight/dp/B095CCD5XT

Thanks gang,

found these fittings: Joywayus 1/4" Hose Barb Bulkhead Fitting Thru-Bulk Head Hex Union Brass Fitting with Flat Washer Gasket Water/Fuel/Air (Pack of 5) https://www.amazon.com/dp/B0BP1WLKBZ/ref=twister_B07XTDKR42?_encoding=UTF8&th=1

to go with these bottles: 17oz/500ml Wide Mouth Plastic Bottles with Airtight Lids, Graduated Food Grade Leak Proof PP Containers Jars for Water Sample Lab Reagent Liquid Medicine Storage (Transparent, 2 Pcs)  https://www.amazon.com/dp/B0DJQTPNSD?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

You do not need a  "vent fitting" on the overflow bottle. 

An small opening, about 2-3mm, in the cap, is sufficient to allow air out as coolant level rises (hot) and back in again, when level drops (cools) & also keeps internal pressure equal to external as aircraft climes & descends .

As long as you do not overfill the bottle, about 1/3-1/2 , there will never be a coolant spill, unless you overheat the engine. Should you overheat the engine you will have bigger worries to attend to, compared with a a coolant spill.

A vent fitting & tube, is a unnecessary  - wont do any harm or good😈