This is a 30 round mag for a Glock 21 (.45 ACP).
Saw it at a local gun show for $60.

Is this the typical price?
Does these work?

I have one that is made by Scherer and it does not work.  It is suppose to hold 25rds of 45ACP.  Mine would only hold 15rds.  If I tried to load more than 15rds the the spring would tangle in the bottom.  

$45 @Lone Wolf

I have had a couple of the 40 cal that would hang-up. The fix is to disassemble the mag and remove any/all plastic from the injection process from the inside at the witness holes with an X-acto knife.

wow, i didn't know they made 30 rounders for 45.

that's cool.

I can assure you that it does not function. Period.

Good information. Thanks.
You guys just saved me $60

Quoted: I can assure you that it does not function. Period.

how bad is this?  will it jam up?  how about if i were to put 28 rounds?  

if it isn't made by glock it will not reliably function.

Quoted: how bad is this?  will it jam up?  how about if i were to put 28 rounds?

The mag only holds 25rds. A friend is picking one up for his G20. I will try to post back with his test.  

Quoted: Quoted: I can assure you that it does not function. Period. how bad is this?  will it jam up?  how about if i were to put 28 rounds?

Beginning, middle and end of the mag it will jam. I believe three or four rounds was most we ever put downrange in one string, and the first one was chambered by hand.

If you want reliable just use the latest 13 round mags with NO extensions not even the +2s.  Wolff XP springs is the only thing I've added to mine.  My G21 has never jammed.  

I used to shoot the G21 in IDPA but lately I find that it seems that I'm waiting for the slide to get done cycling before I can fire again this is also occuring with my SSP gun a 92G Beretta Elite.  So lately I'm shooting my SA 1911 in CDP.  When I get a holster for it I'm going to try my wifes 92G Vertec in SSP, in the meantime I'm experimenting with 14-16lb recoil springs in the Elite to see if that'll speed the return to battery up, I know it'll slow down the rearward slide travel.