Hi Llasi,
I got this sheath from an Army disposals store.Cost me $5.I was told it was for a Sog Dagger.Im not sure which model as I havent done much research into it.I assume it may be one of the "Fusion" brand made in china.There are no logos or tags on it to say who or what it was for.It will take a five inch blade,so the 28 fits okay.
The plastic insert is not kydex but a softish plastic that does not scratch the blade.(This doesnt bother me as this knife will be used on my dive trips as well as on the land)It has two ribs molded internally on each side,so the friction fit is just right for this blade.
The keeper strap is a little tight but this will stretch with wear,or I could remove it and make one a little longer.
I removed some webbing from the rear because it was not functional.I replaced these with an open pouch to hold a 4 x1 inch DMT diamond plate.
The leg lanyard was on it when purchased and works fine.I have also added a lanyard through the holes above the keeper strap similar to the way in is done on the original leather sheath.
Belt loop consists of two flaps with velcro and is similar to that used on the Cold Steel SRK,but without the snap.Pouch on the front is big enough to take a multi-tool or whatever else.
I in no way knock the original sheath supplied with the knife,I feel that for this sheath will be more practical given where it is to be used.Thankyou for the query,hope this helps.