Product Review

You will get:
3 Pieces charging hose with gauge kit includes 2 x BPV-31 bullet piercing tap valve and 1 x R134a charging hose with gauge

BPV-31 bullet piercing tap valve:

Good quality and easy to install. 
The sealing area of the valve is 50 times that of the o-ring. In addition, its sealing force is 180 inch lbs, pressure test at 250 ℉, and torque tested with 500 lbs. 
Corrosion resistant. 

Replace part No.: AP4502525, BPV31D, GPV14, GPV31, GPV38, GPV56, MPV31. Compatible with 1/4 inch, 5/16 inch, 3/8 inch outside diameter pipes. 

Material: metal 
Quantity: 2 packs 
Color: sliver 

R12 R22 charging hose with gauge：

R-134a can be connected to the R-12 / R-22 service port for easy conversion
Built-in safety valve to prevent accidental venting of refrigerant
90 Degree push and lock coupler with auto shut off.
Easy and convenient to use. Gauge has three scale readings of R134, R12 and R22 for your convenience
Fits only those cans with the threat of 1/2 inch. If you wan to to use it to R134a can male thread (7/16 inch), you need one adjusted connector.
Can be applied for home air-conditioning and car air-conditioning to add refrigeration.

Material: copper and rubber
Quantity: 1 piece

Package includes:
2 x BPV-31 bullet piercing tap valve kit
1 x R12 R22 charging hose with gauge

Warm notice:
It is not compatible with refrigerant R134A. Put on your safety glasses and protective gloves before piercing the pipe. 
This is not the original product, the mention of brand names and any related model designation above is only for purposes of demonstrating compatibility.