M48 with through the stock sling keeper in K98 fashion  This sling can also be used for the M24 using two buttons instead of the keeper
and can be adjusted by using one the many holes to  shorten its length.
BK in circle stamped on the keeper and the same mark is on the other end of the sling.  I have several of these slings that are new with no marks at all

SKS 59-59/66
early sling

59/66A1 late model with large sling swivels
Will not fit the early model with small swivels

Another style of M24 Sling this sling is like the M59/66 sling
except for the buckle

One style of buckle