I don't remember which brand, but I paid a reportedly good Calgary gunsmith a goodly amount of money to put one on my stainless 700 in .375H&H.
When I picked it up, he said, "be careful, it doesn't block the sear." I found out what he meant later: if you had it in the middle position and bumped the trigger, it would fire when you moved the safety to the "off" position. My poor cousin, even after an appropriate 'modified safety briefing' was wandering the back 40 and it went off, drilling a cone-shaped hole 12" in diameter and 18" deep, and peeling a good amount of his right thumbtip off.
Do your diligence...