In this product? "OBI univerzális szelep acél 38,5 mm" I've no idea what that "38,5 mm" is referring to. I've no experience also.
Here's the translated text:
OBI Universal Valve Steel 38.5 mm
Item Number: 3231248
Prevents the accumulation of dirt in the drain Made of strong steel Silver-colored, matte finishProduct Description
Item Number: 3231248
The easy-to-use OBI universal valve is a drain filter that captures dirt and other impurities. It can be used in the drains of bathroom and kitchen sinks. It prevents clogging and helps avoid unpleasant odors. Made of silver-colored steel with a matte finish, its surface is smooth and easy to keep clean. Additionally, the material is strong, durable, and heat-resistant. The valve connects with a 41.9 mm (G 1 1/4) thread. A practical plug is provided for sealing the valve.
Technical Specifications
Product Features
Connection: 1 1/4"
Flexible Outlet: No
Material: Steel
Dimensions and Weight (net)
Weight: 58 g
That 1 1/4" is apparently 31.75mm, so not that 38.5mm.
What's the "38.5mm" about? and maybe also if you know what the size of the bolt/screw is?, in case anyone stumbles upon this trying to find that because their threads are ripped. Also, is this really called a valve? this whole kit? Thanks.

