Tactical free float handguard endcap WTB

[bankjob]

I saw this somewhere on the web. It was a forearm end cap that was spiked so the rifle could bite and take a hold of a surface for steadying the rifle. I am in process of piecing together a build and now I can't find the source.

Has anyone seen the endcap I'm talking about and if so where?

Thanks

[Stickman]

I've seen them for railed handguards. NST has some nice ones.