Splicing activity is a function of:
Small Nuclear RNA (SnRNA):

They  belong  to  small  RNAs  of  size  90  to  300 nucleotides
1% of total RNAs
They have ribozyme activity.
Function
mRNA Processing (U1, U2, U4,U5, U6 and U7 as a part of spliceosome)
rRNA processing
Gene regulation.

Harper 30th edition Pg-408,411
mRNA
snRNA
tRNA
rRNA