Why does 1/2 npt require hole size of 21.5 mm or .84" ? such confusing specs/statements abound

NPT or National Pipe Thread Standard sizes can be a bit confusing. 1/2" NPT is not 1/2" diameter. Nor is it the I.D. as others have stated. Hole size will always be greater than the NPT nominal diameter callout.

what is the length of the threaded portion of these glands (useable with nuts) how thick of a mounting surface can these be used on.

Only good for a standard electrical box or about a1/8 th of an inch. For some of my thicker boxes I did tap the with a pipe thread so they would screw in.

Why is the cable range of the 1 1/4 inch (~32mm) listed as max range 25mm?

I believe that if you go to the manufactures web site,that maybe the biggest cable gland that they make. There are other manufactures that make cable glands in larger sizes.

what size do I need for a hole that is 3/8 inch in diameter

Your question needs more information. I believe you are saying is that your 3/8" cable,coax or tubing is that size of 3/8" correct? Now the hole size for the Makerele NPT Cable Gland Kit for 3/8" needs to be 5/8" or .625 in.,the Gland thread end is a little bigger in size of .630 in.,that is .005 larger than 5/8",so you will be fine there. It will fit,due to the plastic of the threads.

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Cord Grip NPT Cable Glands Kit for Electrical Waterproof Box | Black 50pcs, 1/4” 3/8” 1/2” 3/4” 1” 1-1/4”, Waterproof Nylon Strain Relief Connector, Junction Case Connector With Gaskets

Product ID: 288448662

💧IP68 waterproof rating

🔧50pcs multi-size kit

🛡️Durable nylon PA66

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Description

🔌 Secure your cables like a pro—because your projects deserve the best!

BUILT TO LAST - Premium nylon PA66 construction ensures superior durability and resistance to wear.
WATERPROOF CONFIDENCE - IP68 rating means your connections stay protected even underwater or in harsh environments.
EFFORTLESS INSTALLATION - Thread, tighten, and lock—no disassembly needed for a secure, strain-free fit.
WIDE CABLE COMPATIBILITY - Supports cables from 0.10 to 1.2 inches, covering a broad spectrum of wiring demands.
ALL IN ONE CABLE SOLUTION - 50 versatile NPT sizes to fit every project need, from 1/4” to 1-1/4”.

The MAKERELE Cord Grip Cable Glands Kit offers 50 high-quality, waterproof nylon connectors in six NPT sizes, designed for reliable strain relief and protection in electrical boxes. With an IP68 rating and compatibility with a wide range of cable diameters, this kit is perfect for both indoor and outdoor professional applications, ensuring durable, easy-to-install cable management.

Specifications

ASIN	B08R86BHBC
Batteries Included?	No
Batteries Required?	No
Best Sellers Rank	#8,918 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #4 in Electrical Conduit Fittings
Color	Black
Customer Reviews	4.7 4.7 out of 5 stars (1,486)
Date First Available	December 24, 2020
Is Discontinued By Manufacturer	No
Item Weight	1.86 pounds
Item model number	NPT(50)Box6A-B
Manufacturer	Yueqing Maker electric Co.,ltd
Material	nylon
Product Dimensions	10.83 x 6.5 x 2.17 inches
Size	50pcs KIT BOX

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B/.97

Duties & taxes included

In stock

Sold byAmazon PanamaDelivered byDesertcartCustomer service byDesertcartReturns14 days · 30 with PRO

Buyer Protection · Full refund if your order doesn't arrive as described.

Desertcart purchases this item on your behalf and handles shipping, customs, and support to Panama.

Secure transaction

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TrustScore 4.5 | 7,300+ reviews

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