oil filter spacer flush mount?

[GQSWB]

im wanting to upgrade my oil pressure sender and looking at fitting those oil filter spacers so i can haveboth pressure n temp readings.
ive noticed some come with a groove in the surface that an o ring sits in and others are just a flat flush mounting surface, was curious if these still seal well or are they prone to leaking.
and the usual question, are the cheaper ebay ones any good???

[Robo]

Smooth side, is for filter.
O-ring side for the block side of adapter.
As for quality bit hard to say, but really how technical is it an adapter !.
Straight through flow so , long as it has decent ports should be the go you need.
Ask em what are they are rated for if your worried. flow and pressure.
I purchased a remote cooler kit ebay and block fittings were nice and solid, I did however port the holes to improve flow, but that was for Nissan GTR, but I used Earls fittings and better quality hose than ebay supply as a rule.
Cheers

[GQSWB]

thanks for that, i was thinking the same re quality n its good to get a second opinion.. ive actually been surprised with just how good some of the ebay/cheap stuff is, my swivell hub kit just arrived, was from ebay and all top quality (koyo bearings)...